annotate doc/interpreter/numbers.txi @ 20486:4bb41929286b

Deprecate bitmax. * NEWS: Announce deprecation and replacement functions. * scripts/deprecated/bitmax.m: New function. Add deprecation message to docstring. Add deprecation warning to m-file. * scripts/deprecated/module.mk: Add deprecated versions to build system. * libinterp/corefcn/bitfcns.cc: Remove build-in function. Remove function from docstrings. * libinterp/corefcn/data.cc: Remove function from docstrings. * scripts/general/bitcmp.m: Replace bitmax function calls with flintmax. Remove function from docstrings. * scripts/general/bitget.m: Replace bitmax function calls with flintmax. Remove function from docstrings. * scripts/general/bitset.m: Replace bitmax function calls with flintmax. Remove function from docstrings. * scripts/specfun/factor.m: Replace bitmax function calls with flintmax. Remove function from docstrings. * scripts/statistics/distributions/unidpdf.m: Remove function from docstrings. * scripts/general/num2str.m: Replaced function in comment. * doc/interpreter/doccheck/aspell-octave.en.pws: Remove functions from list. * doc/interpreter/numbers.txi: Remove function from manual.
author Kai T. Ohlhus <k.ohlhus@gmail.com>
date Wed, 09 Sep 2015 18:43:52 +0200
parents 4197fc428c7d
children 1ecee53513d7
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1 @c Copyright (C) 1996-2015 John W. Eaton
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2 @c
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3 @c This file is part of Octave.
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4 @c
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5 @c Octave is free software; you can redistribute it and/or modify it
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6 @c under the terms of the GNU General Public License as published by the
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7 @c Free Software Foundation; either version 3 of the License, or (at
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8 @c your option) any later version.
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9 @c
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10 @c Octave is distributed in the hope that it will be useful, but WITHOUT
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11 @c ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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12 @c FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 @c for more details.
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14 @c
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15 @c You should have received a copy of the GNU General Public License
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16 @c along with Octave; see the file COPYING. If not, see
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17 @c <http://www.gnu.org/licenses/>.
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18
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19 @node Numeric Data Types
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20 @chapter Numeric Data Types
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21 @cindex numeric constant
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22 @cindex numeric value
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23
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24 A @dfn{numeric constant} may be a scalar, a vector, or a matrix, and it
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25 may contain complex values.
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26
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27 The simplest form of a numeric constant, a scalar, is a single number
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28 that can be an integer, a decimal fraction, a number in scientific
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29 (exponential) notation, or a complex number. Note that by default numeric
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30 constants are represented within Octave in double-precision floating
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31 point format (complex constants are stored as pairs of double-precision
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32 floating point values). It is, however, possible to represent real
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33 integers as described in @ref{Integer Data Types}. Here are some
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34 examples of real-valued numeric constants, which all have the same
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35 value:
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36
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37 @example
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38 @group
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39 105
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40 1.05e+2
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41 1050e-1
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42 @end group
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43 @end example
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44
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45 To specify complex constants, you can write an expression of the form
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46
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47 @example
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48 @group
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49 3 + 4i
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50 3.0 + 4.0i
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51 0.3e1 + 40e-1i
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52 @end group
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53 @end example
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54
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55 @noindent
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56 all of which are equivalent. The letter @samp{i} in the previous example
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57 stands for the pure imaginary constant, defined as
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58 @tex
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59 $\sqrt{-1}$.
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60 @end tex
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61 @ifnottex
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62 @code{sqrt (-1)}.
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63 @end ifnottex
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64
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65 For Octave to recognize a value as the imaginary part of a complex
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66 constant, a space must not appear between the number and the @samp{i}.
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67 If it does, Octave will print an error message, like this:
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68
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69 @example
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70 @group
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71 octave:13> 3 + 4 i
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72
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73 parse error:
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74
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75 syntax error
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76
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77 >>> 3 + 4 i
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78 ^
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79 @end group
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80 @end example
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81
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82 @noindent
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83 You may also use @samp{j}, @samp{I}, or @samp{J} in place of the
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84 @samp{i} above. All four forms are equivalent.
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85
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86 @DOCSTRING(double)
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87
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88 @DOCSTRING(complex)
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89
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90 @menu
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91 * Matrices::
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92 * Ranges::
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93 * Single Precision Data Types::
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94 * Integer Data Types::
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95 * Bit Manipulations::
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96 * Logical Values::
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97 * Promotion and Demotion of Data Types::
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98 * Predicates for Numeric Objects::
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99 @end menu
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100
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101 @node Matrices
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102 @section Matrices
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103 @cindex matrices
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104
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105 @opindex [
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106 @opindex ]
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107 @opindex ;
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108 @opindex ,
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109
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110 It is easy to define a matrix of values in Octave. The size of the
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111 matrix is determined automatically, so it is not necessary to explicitly
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112 state the dimensions. The expression
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113
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114 @example
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115 a = [1, 2; 3, 4]
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116 @end example
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117
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118 @noindent
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119 results in the matrix
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120 @tex
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121 $$ a = \left[ \matrix{ 1 & 2 \cr 3 & 4 } \right] $$
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122 @end tex
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123 @ifnottex
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124
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125 @example
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126 @group
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127
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128 / \
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129 | 1 2 |
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130 a = | |
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131 | 3 4 |
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132 \ /
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133
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134 @end group
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135 @end example
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136
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137 @end ifnottex
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138
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139 Elements of a matrix may be arbitrary expressions, provided that the
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140 dimensions all make sense when combining the various pieces. For
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141 example, given the above matrix, the expression
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142
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143 @example
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144 [ a, a ]
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145 @end example
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146
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147 @noindent
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148 produces the matrix
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149
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150 @example
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151 @group
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152 ans =
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153
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154 1 2 1 2
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155 3 4 3 4
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156 @end group
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157 @end example
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158
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159 @noindent
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160 but the expression
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161
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162 @example
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163 [ a, 1 ]
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164 @end example
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165
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166 @noindent
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167 produces the error
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168
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169 @example
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170 error: number of rows must match (1 != 2) near line 13, column 6
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171 @end example
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172
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173 @noindent
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174 (assuming that this expression was entered as the first thing on line
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175 13, of course).
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176
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177 Inside the square brackets that delimit a matrix expression, Octave
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178 looks at the surrounding context to determine whether spaces and newline
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179 characters should be converted into element and row separators, or
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180 simply ignored, so an expression like
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181
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182 @example
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183 @group
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184 a = [ 1 2
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185 3 4 ]
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186 @end group
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187 @end example
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188
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189 @noindent
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190 will work. However, some possible sources of confusion remain. For
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191 example, in the expression
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192
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193 @example
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194 [ 1 - 1 ]
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195 @end example
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196
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197 @noindent
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198 the @samp{-} is treated as a binary operator and the result is the
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199 scalar 0, but in the expression
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200
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201 @example
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202 [ 1 -1 ]
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203 @end example
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204
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205 @noindent
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206 the @samp{-} is treated as a unary operator and the result is the
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207 vector @code{[ 1, -1 ]}. Similarly, the expression
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208
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209 @example
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210 [ sin (pi) ]
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211 @end example
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212
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213 @noindent
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214 will be parsed as
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215
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216 @example
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217 [ sin, (pi) ]
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218 @end example
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219
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220 @noindent
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221 and will result in an error since the @code{sin} function will be
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222 called with no arguments. To get around this, you must omit the space
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223 between @code{sin} and the opening parenthesis, or enclose the
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224 expression in a set of parentheses:
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225
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226 @example
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227 [ (sin (pi)) ]
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228 @end example
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229
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230 Whitespace surrounding the single quote character (@samp{'}, used as a
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231 transpose operator and for delimiting character strings) can also cause
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232 confusion. Given @code{a = 1}, the expression
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233
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234 @example
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235 [ 1 a' ]
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236 @end example
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237
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238 @noindent
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239 results in the single quote character being treated as a
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240 transpose operator and the result is the vector @code{[ 1, 1 ]}, but the
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241 expression
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242
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243 @example
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244 [ 1 a ' ]
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245 @end example
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246
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247 @noindent
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248 produces the error message
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249
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250 @example
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251 @group
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252 parse error:
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253
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254 syntax error
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255
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256 >>> [ 1 a ' ]
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257 ^
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258 @end group
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259 @end example
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260
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261 @noindent
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262 because not doing so would cause trouble when parsing the valid expression
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263
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264 @example
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265 [ a 'foo' ]
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266 @end example
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267
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268 For clarity, it is probably best to always use commas and semicolons to
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269 separate matrix elements and rows.
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270
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271 The maximum number of elements in a matrix is fixed when Octave is compiled.
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272 The allowable number can be queried with the function @code{sizemax}. Note
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273 that other factors, such as the amount of memory available on your machine,
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274 may limit the maximum size of matrices to something smaller.
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275
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276 @DOCSTRING(sizemax)
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277
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278 When you type a matrix or the name of a variable whose value is a
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279 matrix, Octave responds by printing the matrix in with neatly aligned
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280 rows and columns. If the rows of the matrix are too large to fit on the
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281 screen, Octave splits the matrix and displays a header before each
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282 section to indicate which columns are being displayed. You can use the
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283 following variables to control the format of the output.
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284
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285 @DOCSTRING(output_max_field_width)
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286
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287 @DOCSTRING(output_precision)
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288
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289 It is possible to achieve a wide range of output styles by using
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290 different values of @code{output_precision} and
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291 @code{output_max_field_width}. Reasonable combinations can be set using
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292 the @code{format} function. @xref{Basic Input and Output}.
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293
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294 @DOCSTRING(split_long_rows)
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295
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296 Octave automatically switches to scientific notation when values become
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297 very large or very small. This guarantees that you will see several
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298 significant figures for every value in a matrix. If you would prefer to
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299 see all values in a matrix printed in a fixed point format, you can set
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300 the built-in variable @code{fixed_point_format} to a nonzero value. But
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301 doing so is not recommended, because it can produce output that can
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302 easily be misinterpreted.
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303
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304 @DOCSTRING(fixed_point_format)
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305
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306 @menu
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307 * Empty Matrices::
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308 @end menu
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309
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310 @node Empty Matrices
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311 @subsection Empty Matrices
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312
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313 A matrix may have one or both dimensions zero, and operations on empty
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314 matrices are handled as described by @nospell{Carl de Boor} in
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315 @cite{An Empty Exercise}, SIGNUM, Volume 25, pages 2-6, 1990 and
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316 @nospell{C. N. Nett and W. M. Haddad}, in
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317 @cite{A System-Theoretic Appropriate Realization of the Empty Matrix Concept},
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318 IEEE Transactions on Automatic Control, Volume 38, Number 5, May 1993.
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319 @tex
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320 Briefly, given a scalar $s$, an $m\times n$ matrix $M_{m\times n}$,
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321 and an $m\times n$ empty matrix $[\,]_{m\times n}$ (with either one or
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322 both dimensions equal to zero), the following are true:
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323 $$
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324 \eqalign{%
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325 s \cdot [\,]_{m\times n} = [\,]_{m\times n} \cdot s &= [\,]_{m\times n}\cr
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326 [\,]_{m\times n} + [\,]_{m\times n} &= [\,]_{m\times n}\cr
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327 [\,]_{0\times m} \cdot M_{m\times n} &= [\,]_{0\times n}\cr
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328 M_{m\times n} \cdot [\,]_{n\times 0} &= [\,]_{m\times 0}\cr
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329 [\,]_{m\times 0} \cdot [\,]_{0\times n} &= 0_{m\times n}}
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330 $$
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331 @end tex
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332 @ifnottex
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333 Briefly, given a scalar @var{s}, an @var{m} by
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334 @var{n} matrix @code{M(mxn)}, and an @var{m} by @var{n} empty matrix
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335 @code{[](mxn)} (with either one or both dimensions equal to zero), the
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336 following are true:
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337
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338 @example
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339 @group
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340 s * [](mxn) = [](mxn) * s = [](mxn)
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341
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342 [](mxn) + [](mxn) = [](mxn)
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343
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344 [](0xm) * M(mxn) = [](0xn)
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345
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346 M(mxn) * [](nx0) = [](mx0)
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347
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348 [](mx0) * [](0xn) = 0(mxn)
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349 @end group
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350 @end example
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351
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352 @end ifnottex
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353
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354 By default, dimensions of the empty matrix are printed along with the
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355 empty matrix symbol, @samp{[]}. The built-in variable
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356 @code{print_empty_dimensions} controls this behavior.
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357
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358 @DOCSTRING(print_empty_dimensions)
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359
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360 Empty matrices may also be used in assignment statements as a convenient
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361 way to delete rows or columns of matrices.
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362 @xref{Assignment Ops,,Assignment Expressions}.
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363
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364 When Octave parses a matrix expression, it examines the elements of the
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365 list to determine whether they are all constants. If they are, it
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366 replaces the list with a single matrix constant.
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367
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368 @node Ranges
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369 @section Ranges
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370 @cindex range expressions
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371 @cindex expression, range
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372
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373 @opindex :
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374
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375 A @dfn{range} is a convenient way to write a row vector with evenly
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376 spaced elements. A range expression is defined by the value of the first
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377 element in the range, an optional value for the increment between
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378 elements, and a maximum value which the elements of the range will not
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379 exceed. The base, increment, and limit are separated by colons (the
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380 @samp{:} character) and may contain any arithmetic expressions and
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381 function calls. If the increment is omitted, it is assumed to be 1.
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382 For example, the range
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383
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384 @example
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385 1 : 5
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386 @end example
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387
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388 @noindent
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389 defines the set of values @samp{[ 1, 2, 3, 4, 5 ]}, and the range
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390
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391 @example
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392 1 : 3 : 5
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393 @end example
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394
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395 @noindent
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396 defines the set of values @samp{[ 1, 4 ]}.
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397
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398 Although a range constant specifies a row vector, Octave does @emph{not}
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399 normally convert range constants to vectors unless it is necessary to do so.
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400 This allows you to write a constant like @samp{1 : 10000} without using
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401 80,000 bytes of storage on a typical 32-bit workstation.
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402
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403 A common example of when it does become necessary to convert ranges into
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404 vectors occurs when they appear within a vector (i.e., inside square
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405 brackets). For instance, whereas
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406
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407 @example
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408 x = 0 : 0.1 : 1;
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409 @end example
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410
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411 @noindent
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412 defines @var{x} to be a variable of type @code{range} and occupies 24
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413 bytes of memory, the expression
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414
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415 @example
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416 y = [ 0 : 0.1 : 1];
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417 @end example
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418
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419 @noindent
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420 defines @var{y} to be of type @code{matrix} and occupies 88 bytes of
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421 memory.
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422
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423 This space saving optimization may be disabled using the function
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424 @dfn{disable_range}.
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425
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426 @DOCSTRING(disable_range)
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427
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428 Note that the upper (or lower, if the increment is negative) bound on
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429 the range is not always included in the set of values, and that ranges
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430 defined by floating point values can produce surprising results because
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431 Octave uses floating point arithmetic to compute the values in the
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432 range. If it is important to include the endpoints of a range and the
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433 number of elements is known, you should use the @code{linspace} function
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434 instead (@pxref{Special Utility Matrices}).
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435
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436 When adding a scalar to a range, subtracting a scalar from it (or subtracting a
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437 range from a scalar) and multiplying by scalar, Octave will attempt to avoid
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438 unpacking the range and keep the result as a range, too, if it can determine
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439 that it is safe to do so. For instance, doing
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440
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441 @example
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442 a = 2*(1:1e7) - 1;
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443 @end example
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444
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445 @noindent
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446 will produce the same result as @samp{1:2:2e7-1}, but without ever forming a
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447 vector with ten million elements.
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448
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449 Using zero as an increment in the colon notation, as @samp{1:0:1} is not
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450 allowed, because a division by zero would occur in determining the number of
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451 range elements. However, ranges with zero increment (i.e., all elements equal)
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452 are useful, especially in indexing, and Octave allows them to be constructed
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453 using the built-in function @dfn{ones}. Note that because a range must be a row
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454 vector, @samp{ones (1, 10)} produces a range, while @samp{ones (10, 1)} does
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455 not.
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456
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457 When Octave parses a range expression, it examines the elements of the
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458 expression to determine whether they are all constants. If they are, it
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459 replaces the range expression with a single range constant.
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460
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461 @node Single Precision Data Types
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462 @section Single Precision Data Types
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463
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464 Octave includes support for single precision data types, and most of the
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465 functions in Octave accept single precision values and return single
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466 precision answers. A single precision variable is created with the
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467 @code{single} function.
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468
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469 @DOCSTRING(single)
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470
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471 for example:
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472
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diff changeset
473 @example
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diff changeset
474 @group
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diff changeset
475 sngl = single (rand (2, 2))
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parents: 17744
diff changeset
476 @result{} sngl =
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parents: 8347
diff changeset
477 0.37569 0.92982
0eb83938c8bc Trivial fixes in numbers.txi
Thorsten Meyer <thorsten.meyier@gmx.de>
parents: 8347
diff changeset
478 0.11962 0.50876
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diff changeset
479 class (sngl)
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parents: 7638
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480 @result{} single
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481 @end group
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482 @end example
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David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
483
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484 Many functions can also return single precision values directly. For
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David Bateman <dbateman@free.fr>
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diff changeset
485 example
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David Bateman <dbateman@free.fr>
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diff changeset
486
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487 @example
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diff changeset
488 @group
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489 ones (2, 2, "single")
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
490 zeros (2, 2, "single")
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
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491 eye (2, 2, "single")
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David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
492 rand (2, 2, "single")
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
493 NaN (2, 2, "single")
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
494 NA (2, 2, "single")
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
495 Inf (2, 2, "single")
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diff changeset
496 @end group
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497 @end example
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498
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diff changeset
499 @noindent
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David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
500 will all return single precision matrices.
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
501
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502 @node Integer Data Types
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
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diff changeset
503 @section Integer Data Types
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parents: 6501
diff changeset
504
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parents: 6550
diff changeset
505 Octave supports integer matrices as an alternative to using double
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Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
506 precision. It is possible to use both signed and unsigned integers
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parents: 8920
diff changeset
507 represented by 8, 16, 32, or 64 bits. It should be noted that most
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508 computations require floating point data, meaning that integers will
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parents: 8920
diff changeset
509 often change type when involved in numeric computations. For this
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diff changeset
510 reason integers are most often used to store data, and not for
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diff changeset
511 calculations.
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diff changeset
512
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diff changeset
513 In general most integer matrices are created by casting
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parents: 8920
diff changeset
514 existing matrices to integers. The following example shows how to cast
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diff changeset
515 a matrix into 32 bit integers.
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diff changeset
516
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diff changeset
517 @example
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parents: 9158
diff changeset
518 @group
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519 float = rand (2, 2)
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diff changeset
520 @result{} float = 0.37569 0.92982
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diff changeset
521 0.11962 0.50876
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diff changeset
522 integer = int32 (float)
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diff changeset
523 @result{} integer = 0 1
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diff changeset
524 0 1
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parents: 9158
diff changeset
525 @end group
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diff changeset
526 @end example
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diff changeset
527
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
528 @noindent
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parents: 6550
diff changeset
529 As can be seen, floating point values are rounded to the nearest integer
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
530 when converted.
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diff changeset
531
6549
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diff changeset
532 @DOCSTRING(isinteger)
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parents: 6501
diff changeset
533
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
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diff changeset
534 @DOCSTRING(int8)
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
jwe
parents: 6501
diff changeset
535
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
jwe
parents: 6501
diff changeset
536 @DOCSTRING(uint8)
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
jwe
parents: 6501
diff changeset
537
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
jwe
parents: 6501
diff changeset
538 @DOCSTRING(int16)
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jwe
parents: 6501
diff changeset
539
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
jwe
parents: 6501
diff changeset
540 @DOCSTRING(uint16)
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
jwe
parents: 6501
diff changeset
541
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
jwe
parents: 6501
diff changeset
542 @DOCSTRING(int32)
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jwe
parents: 6501
diff changeset
543
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
jwe
parents: 6501
diff changeset
544 @DOCSTRING(uint32)
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jwe
parents: 6501
diff changeset
545
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
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parents: 6501
diff changeset
546 @DOCSTRING(int64)
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
jwe
parents: 6501
diff changeset
547
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
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diff changeset
548 @DOCSTRING(uint64)
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parents: 6501
diff changeset
549
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parents: 6501
diff changeset
550 @DOCSTRING(intmax)
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
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parents: 6501
diff changeset
551
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
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diff changeset
552 @DOCSTRING(intmin)
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
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diff changeset
553
17390
4bcd301754ce Add Matlab-compatible flintmax function
Mike Miller <mtmiller@ieee.org>
parents: 17281
diff changeset
554 @DOCSTRING(flintmax)
4bcd301754ce Add Matlab-compatible flintmax function
Mike Miller <mtmiller@ieee.org>
parents: 17281
diff changeset
555
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parents: 6620
diff changeset
556 @menu
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jwe
parents: 6620
diff changeset
557 * Integer Arithmetic::
0d69a50fc5a9 [project @ 2007-05-15 20:17:27 by jwe]
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parents: 6620
diff changeset
558 @end menu
0d69a50fc5a9 [project @ 2007-05-15 20:17:27 by jwe]
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diff changeset
559
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diff changeset
560 @node Integer Arithmetic
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
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parents: 6550
diff changeset
561 @subsection Integer Arithmetic
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
562
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
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parents: 6550
diff changeset
563 While many numerical computations can't be carried out in integers,
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
564 Octave does support basic operations like addition and multiplication
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Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
565 on integers. The operators @code{+}, @code{-}, @code{.*}, and @code{./}
58604c45ca74 Cleanup of data types related documentation
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parents: 8920
diff changeset
566 work on integers of the same type. So, it is possible to add two 32 bit
6620
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jwe
parents: 6550
diff changeset
567 integers, but not to add a 32 bit integer and a 16 bit integer.
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
568
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
569 When doing integer arithmetic one should consider the possibility of
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parents: 8920
diff changeset
570 underflow and overflow. This happens when the result of the computation
58604c45ca74 Cleanup of data types related documentation
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parents: 8920
diff changeset
571 can't be represented using the chosen integer type. As an example it is
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diff changeset
572 not possible to represent the result of @math{10 - 20} when using
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parents: 8920
diff changeset
573 unsigned integers. Octave makes sure that the result of integer
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parents: 8920
diff changeset
574 computations is the integer that is closest to the true result. So, the
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diff changeset
575 result of @math{10 - 20} when using unsigned integers is zero.
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diff changeset
576
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
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parents: 6550
diff changeset
577 When doing integer division Octave will round the result to the nearest
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parents: 8920
diff changeset
578 integer. This is different from most programming languages, where the
58604c45ca74 Cleanup of data types related documentation
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parents: 8920
diff changeset
579 result is often floored to the nearest integer. So, the result of
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Rik <octave@nomad.inbox5.com>
parents: 14402
diff changeset
580 @code{int32 (5) ./ int32 (8)} is @code{1}.
6620
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581
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David Bateman <dbateman@free.fr>
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diff changeset
582 @DOCSTRING(idivide)
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David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
583
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parents: 6778
diff changeset
584 @node Bit Manipulations
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
585 @section Bit Manipulations
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
586
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
587 Octave provides a number of functions for the manipulation of numeric
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Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
588 values on a bit by bit basis. The basic functions to set and obtain the
6781
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diff changeset
589 values of individual bits are @code{bitset} and @code{bitget}.
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
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diff changeset
590
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diff changeset
591 @DOCSTRING(bitset)
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dbateman
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diff changeset
592
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parents: 6778
diff changeset
593 @DOCSTRING(bitget)
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
594
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
595 The arguments to all of Octave's bitwise operations can be scalar or
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
596 arrays, except for @code{bitcmp}, whose @var{k} argument must a
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parents: 8920
diff changeset
597 scalar. In the case where more than one argument is an array, then all
6781
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parents: 6778
diff changeset
598 arguments must have the same shape, and the bitwise operator is applied
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parents: 8920
diff changeset
599 to each of the elements of the argument individually. If at least one
6781
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dbateman
parents: 6778
diff changeset
600 argument is a scalar and one an array, then the scalar argument is
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parents: 8920
diff changeset
601 duplicated. Therefore
6781
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dbateman
parents: 6778
diff changeset
602
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
603 @example
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
604 bitget (100, 8:-1:1)
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
605 @end example
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
606
10846
a4f482e66b65 Grammarcheck more of the documentation.
Rik <octave@nomad.inbox5.com>
parents: 10828
diff changeset
607 @noindent
6781
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dbateman
parents: 6778
diff changeset
608 is the same as
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
609
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
610 @example
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
611 bitget (100 * ones (1, 8), 8:-1:1)
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
612 @end example
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
613
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
614 It should be noted that all values passed to the bit manipulation
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parents: 8920
diff changeset
615 functions of Octave are treated as integers. Therefore, even though the
6781
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
616 example for @code{bitset} above passes the floating point value
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
617 @code{10}, it is treated as the bits @code{[1, 0, 1, 0]} rather than the
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
618 bits of the native floating point format representation of @code{10}.
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dbateman
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diff changeset
619
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Brian Gough <bjg@network-theory.co.uk>
parents: 8534
diff changeset
620 As the maximum value that can be represented by a number is important
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parents: 6778
diff changeset
621 for bit manipulation, particularly when forming masks, Octave supplies
20486
4bb41929286b Deprecate bitmax.
Kai T. Ohlhus <k.ohlhus@gmail.com>
parents: 19697
diff changeset
622 two functions 'flintmax' for floating point integers, and 'intmax'.
6781
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diff changeset
623
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Rik <rik@octave.org>
parents: 17152
diff changeset
624 Octave also includes the basic bitwise 'and', 'or', and 'exclusive or'
6781
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dbateman
parents: 6778
diff changeset
625 operators.
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
626
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
627 @DOCSTRING(bitand)
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
628
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
629 @DOCSTRING(bitor)
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
630
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
631 @DOCSTRING(bitxor)
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
632
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parents: 8325
diff changeset
633 The bitwise 'not' operator is a unary operator that performs a logical
9036
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parents: 8920
diff changeset
634 negation of each of the bits of the value. For this to make sense, the
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
635 mask against which the value is negated must be defined. Octave's
6781
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
636 bitwise 'not' operator is @code{bitcmp}.
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
637
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
638 @DOCSTRING(bitcmp)
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
639
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parents: 8325
diff changeset
640 Octave also includes the ability to left-shift and right-shift values bitwise.
6781
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
641
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
642 @DOCSTRING(bitshift)
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
643
9036
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Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
644 Bits that are shifted out of either end of the value are lost. Octave
8347
fa78cb8d8a5c corrections for typos
Brian Gough<bjg@network-theory.co.uk>
parents: 8325
diff changeset
645 also uses arithmetic shifts, where the sign bit of the value is kept
10828
322f43e0e170 Grammarcheck .txi documentation files.
Rik <octave@nomad.inbox5.com>
parents: 10791
diff changeset
646 during a right shift. For example:
6781
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
647
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
648 @example
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
649 @group
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
650 bitshift (-10, -1)
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
651 @result{} -5
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
652 bitshift (int8 (-1), -1)
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
653 @result{} -1
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
654 @end group
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
655 @end example
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
656
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
657 Note that @code{bitshift (int8 (-1), -1)} is @code{-1} since the bit
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
658 representation of @code{-1} in the @code{int8} data type is @code{[1, 1,
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
659 1, 1, 1, 1, 1, 1]}.
3058060c560f [project @ 2007-07-19 08:07:31 by dbateman]
dbateman
parents: 6778
diff changeset
660
4167
aae05d51353c [project @ 2002-11-12 02:52:50 by jwe]
jwe
parents: 4029
diff changeset
661 @node Logical Values
3428
5b77cf82393c [project @ 2000-01-14 02:54:53 by jwe]
jwe
parents: 3321
diff changeset
662 @section Logical Values
5b77cf82393c [project @ 2000-01-14 02:54:53 by jwe]
jwe
parents: 3321
diff changeset
663
9036
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
664 Octave has built-in support for logical values, i.e., variables that
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
665 are either @code{true} or @code{false}. When comparing two variables,
6620
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
666 the result will be a logical value whose value depends on whether or
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
667 not the comparison is true.
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
668
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
669 The basic logical operations are @code{&}, @code{|}, and @code{!},
8347
fa78cb8d8a5c corrections for typos
Brian Gough<bjg@network-theory.co.uk>
parents: 8325
diff changeset
670 which correspond to ``Logical And'', ``Logical Or'', and ``Logical
9036
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
671 Negation''. These operations all follow the usual rules of logic.
6620
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
672
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
673 It is also possible to use logical values as part of standard numerical
9036
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
674 calculations. In this case @code{true} is converted to @code{1}, and
6620
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
675 @code{false} to 0, both represented using double precision floating
9036
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
676 point numbers. So, the result of @code{true*22 - false/6} is @code{22}.
6620
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
677
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
678 Logical values can also be used to index matrices and cell arrays.
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
679 When indexing with a logical array the result will be a vector containing
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
680 the values corresponding to @code{true} parts of the logical array.
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
681 The following example illustrates this.
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
682
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
683 @example
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
684 @group
6620
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
685 data = [ 1, 2; 3, 4 ];
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
686 idx = (data <= 2);
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
687 data(idx)
9136
537a73861cb7 Fix small mistake in example.
Ansgar Burchard <ansgar@43-1.org>
parents: 9036
diff changeset
688 @result{} ans = [ 1; 2 ]
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
689 @end group
6620
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
690 @end example
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
691
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
692 @noindent
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
693 Instead of creating the @code{idx} array it is possible to replace
11376
567ca09a97aa Remove obsolete documentation about 64-bit integer arithmetic.
Rik <octave@nomad.inbox5.com>
parents: 11179
diff changeset
694 @code{data(idx)} with @w{@code{data( data <= 2 )}} in the above code.
6620
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
695
8828
8463d1a2e544 Doc fixes.
Brian Gough <bjg@network-theory.co.uk>
parents: 8534
diff changeset
696 Logical values can also be constructed by
6620
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
697 casting numeric objects to logical values, or by using the @code{true}
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
698 or @code{false} functions.
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
699
6549
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
jwe
parents: 6501
diff changeset
700 @DOCSTRING(logical)
5a5a09d7deb8 [project @ 2007-04-20 06:55:29 by jwe]
jwe
parents: 6501
diff changeset
701
3428
5b77cf82393c [project @ 2000-01-14 02:54:53 by jwe]
jwe
parents: 3321
diff changeset
702 @DOCSTRING(true)
5b77cf82393c [project @ 2000-01-14 02:54:53 by jwe]
jwe
parents: 3321
diff changeset
703
5b77cf82393c [project @ 2000-01-14 02:54:53 by jwe]
jwe
parents: 3321
diff changeset
704 @DOCSTRING(false)
5b77cf82393c [project @ 2000-01-14 02:54:53 by jwe]
jwe
parents: 3321
diff changeset
705
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
706 @node Promotion and Demotion of Data Types
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
707 @section Promotion and Demotion of Data Types
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
708
10828
322f43e0e170 Grammarcheck .txi documentation files.
Rik <octave@nomad.inbox5.com>
parents: 10791
diff changeset
709 Many operators and functions can work with mixed data types. For example,
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
710
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
711 @example
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
712 @group
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
713 uint8 (1) + 1
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
714 @result{} 2
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
715 @end group
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
716 @end example
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
717
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
718 @noindent
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
719 where the above operator works with an 8-bit integer and a double precision
9036
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
720 value and returns an 8-bit integer value. Note that the type is demoted
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
721 to an 8-bit integer, rather than promoted to a double precision value as
9036
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
722 might be expected. The reason is that if Octave promoted values in
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
723 expressions like the above with all numerical constants would need to be
9036
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
724 explicitly cast to the appropriate data type like
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
725
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
726 @example
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
727 @group
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
728 uint8 (1) + uint8 (1)
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
729 @result{} 2
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
730 @end group
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
731 @end example
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
732
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
733 @noindent
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
734 which becomes difficult for the user to apply uniformly and might allow
9036
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
735 hard to find bugs to be introduced. The same applies to single precision
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
736 values where a mixed operation such as
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
737
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
738 @example
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
739 @group
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
740 single (1) + 1
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
741 @result{} 2
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
742 @end group
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
743 @end example
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
744
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
745 @noindent
9036
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
746 returns a single precision value. The mixed operations that are valid
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
747 and their returned data types are
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
748
7989
23c248d415b5 Various doc fixes. Readd cellidx
David Bateman <dbateman@free.fr>
parents: 7984
diff changeset
749 @multitable @columnfractions .2 .3 .3 .2
19593
446c46af4b42 strip trailing whitespace from most source files
John W. Eaton <jwe@octave.org>
parents: 17744
diff changeset
750 @headitem @tab Mixed Operation @tab Result @tab
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
751 @item @tab double OP single @tab single @tab
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
752 @item @tab double OP integer @tab integer @tab
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
753 @item @tab double OP char @tab double @tab
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
754 @item @tab double OP logical @tab double @tab
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
755 @item @tab single OP integer @tab integer @tab
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
756 @item @tab single OP char @tab single @tab
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
757 @item @tab single OP logical @tab single @tab
7989
23c248d415b5 Various doc fixes. Readd cellidx
David Bateman <dbateman@free.fr>
parents: 7984
diff changeset
758 @end multitable
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
759
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
760 The same logic applies to functions with mixed arguments such as
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
761
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
762 @example
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
763 @group
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
764 min (single (1), 0)
7989
23c248d415b5 Various doc fixes. Readd cellidx
David Bateman <dbateman@free.fr>
parents: 7984
diff changeset
765 @result{} 0
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
766 @end group
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
767 @end example
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
768
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
769 @noindent
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
770 where the returned value is single precision.
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
771
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
772 In the case of mixed type indexed assignments, the type is not
10828
322f43e0e170 Grammarcheck .txi documentation files.
Rik <octave@nomad.inbox5.com>
parents: 10791
diff changeset
773 changed. For example,
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
774
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
775 @example
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
776 @group
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
777 x = ones (2, 2);
14402
cbcaf5602469 doc: Make spacing nicer for Strings chapter of manual.
Rik <octave@nomad.inbox5.com>
parents: 14138
diff changeset
778 x(1, 1) = single (2)
cbcaf5602469 doc: Make spacing nicer for Strings chapter of manual.
Rik <octave@nomad.inbox5.com>
parents: 14138
diff changeset
779 @result{} x = 2 1
cbcaf5602469 doc: Make spacing nicer for Strings chapter of manual.
Rik <octave@nomad.inbox5.com>
parents: 14138
diff changeset
780 1 1
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
781 @end group
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
782 @end example
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
783
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
784 @noindent
19593
446c46af4b42 strip trailing whitespace from most source files
John W. Eaton <jwe@octave.org>
parents: 17744
diff changeset
785 where @code{x} remains of the double precision type.
7984
bbaa5d7d0143 Some documentation updates
David Bateman <dbateman@free.fr>
parents: 7638
diff changeset
786
4167
aae05d51353c [project @ 2002-11-12 02:52:50 by jwe]
jwe
parents: 4029
diff changeset
787 @node Predicates for Numeric Objects
3294
bfe1573bd2ae [project @ 1999-10-19 10:06:07 by jwe]
jwe
parents:
diff changeset
788 @section Predicates for Numeric Objects
bfe1573bd2ae [project @ 1999-10-19 10:06:07 by jwe]
jwe
parents:
diff changeset
789
6620
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
790 Since the type of a variable may change during the execution of a
9036
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
791 program, it can be necessary to do type checking at run-time. Doing this
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
792 also allows you to change the behavior of a function depending on the
58604c45ca74 Cleanup of data types related documentation
Rik <rdrider0-list@yahoo.com>
parents: 8920
diff changeset
793 type of the input. As an example, this naive implementation of @code{abs}
7001
8b0cfeb06365 [project @ 2007-10-10 18:02:59 by jwe]
jwe
parents: 6781
diff changeset
794 returns the absolute value of the input if it is a real number, and the
6620
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
795 length of the input if it is a complex number.
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
796
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
797 @example
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
798 @group
6620
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
799 function a = abs (x)
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
800 if (isreal (x))
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
801 a = sign (x) .* x;
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
802 elseif (iscomplex (x))
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
803 a = sqrt (real(x).^2 + imag(x).^2);
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
804 endif
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
805 endfunction
9209
923c7cb7f13f Simplify TeXinfo files by eliminating redundant @iftex followed by @tex construction.
Rik <rdrider0-list@yahoo.com>
parents: 9158
diff changeset
806 @end group
6620
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
807 @end example
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
808
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
809 The following functions are available for determining the type of a
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
810 variable.
bf4bdc21dc8d [project @ 2007-05-14 17:35:46 by jwe]
jwe
parents: 6550
diff changeset
811
3428
5b77cf82393c [project @ 2000-01-14 02:54:53 by jwe]
jwe
parents: 3321
diff changeset
812 @DOCSTRING(isnumeric)
5b77cf82393c [project @ 2000-01-14 02:54:53 by jwe]
jwe
parents: 3321
diff changeset
813
18900
49961d67e4b9 Add new matrix functions (isdiag, isbanded, istril, istriu) (bug #42688).
Massimiliano Fasi <massimiliano.fasi@gmail.com>
parents: 17744
diff changeset
814 @DOCSTRING(islogical)
49961d67e4b9 Add new matrix functions (isdiag, isbanded, istril, istriu) (bug #42688).
Massimiliano Fasi <massimiliano.fasi@gmail.com>
parents: 17744
diff changeset
815
12581
c8be316f9543 Group commonly used isXXX functions together in documentation.
Rik <octave@nomad.inbox5.com>
parents: 12488
diff changeset
816 @DOCSTRING(isfloat)
3428
5b77cf82393c [project @ 2000-01-14 02:54:53 by jwe]
jwe
parents: 3321
diff changeset
817
12581
c8be316f9543 Group commonly used isXXX functions together in documentation.
Rik <octave@nomad.inbox5.com>
parents: 12488
diff changeset
818 @DOCSTRING(isreal)
7638
2df457529cfa implement expm1 and log1p functions
Jaroslav Hajek <highegg@gmail.com>
parents: 7018
diff changeset
819
4029
2cc57b6169cf [project @ 2002-08-09 07:36:15 by jwe]
jwe
parents: 3920
diff changeset
820 @DOCSTRING(iscomplex)
3428
5b77cf82393c [project @ 2000-01-14 02:54:53 by jwe]
jwe
parents: 3321
diff changeset
821
4029
2cc57b6169cf [project @ 2002-08-09 07:36:15 by jwe]
jwe
parents: 3920
diff changeset
822 @DOCSTRING(ismatrix)
3294
bfe1573bd2ae [project @ 1999-10-19 10:06:07 by jwe]
jwe
parents:
diff changeset
823
4029
2cc57b6169cf [project @ 2002-08-09 07:36:15 by jwe]
jwe
parents: 3920
diff changeset
824 @DOCSTRING(isvector)
3294
bfe1573bd2ae [project @ 1999-10-19 10:06:07 by jwe]
jwe
parents:
diff changeset
825
12488
bea828c03969 Add new isrow, iscolumn functions.
Rik <octave@nomad.inbox5.com>
parents: 12190
diff changeset
826 @DOCSTRING(isrow)
bea828c03969 Add new isrow, iscolumn functions.
Rik <octave@nomad.inbox5.com>
parents: 12190
diff changeset
827
bea828c03969 Add new isrow, iscolumn functions.
Rik <octave@nomad.inbox5.com>
parents: 12190
diff changeset
828 @DOCSTRING(iscolumn)
bea828c03969 Add new isrow, iscolumn functions.
Rik <octave@nomad.inbox5.com>
parents: 12190
diff changeset
829
4029
2cc57b6169cf [project @ 2002-08-09 07:36:15 by jwe]
jwe
parents: 3920
diff changeset
830 @DOCSTRING(isscalar)
3294
bfe1573bd2ae [project @ 1999-10-19 10:06:07 by jwe]
jwe
parents:
diff changeset
831
4029
2cc57b6169cf [project @ 2002-08-09 07:36:15 by jwe]
jwe
parents: 3920
diff changeset
832 @DOCSTRING(issquare)
3294
bfe1573bd2ae [project @ 1999-10-19 10:06:07 by jwe]
jwe
parents:
diff changeset
833
4029
2cc57b6169cf [project @ 2002-08-09 07:36:15 by jwe]
jwe
parents: 3920
diff changeset
834 @DOCSTRING(issymmetric)
3428
5b77cf82393c [project @ 2000-01-14 02:54:53 by jwe]
jwe
parents: 3321
diff changeset
835
11431
0d9640d755b1 Improve docstrings for all isXXX functions.
Rik <octave@nomad.inbox5.com>
parents: 11403
diff changeset
836 @DOCSTRING(ishermitian)
0d9640d755b1 Improve docstrings for all isXXX functions.
Rik <octave@nomad.inbox5.com>
parents: 11403
diff changeset
837
6550
1b7a6061a05d [project @ 2007-04-20 07:40:26 by jwe]
jwe
parents: 6549
diff changeset
838 @DOCSTRING(isdefinite)
1b7a6061a05d [project @ 2007-04-20 07:40:26 by jwe]
jwe
parents: 6549
diff changeset
839
18900
49961d67e4b9 Add new matrix functions (isdiag, isbanded, istril, istriu) (bug #42688).
Massimiliano Fasi <massimiliano.fasi@gmail.com>
parents: 17744
diff changeset
840 @DOCSTRING(isbanded)
49961d67e4b9 Add new matrix functions (isdiag, isbanded, istril, istriu) (bug #42688).
Massimiliano Fasi <massimiliano.fasi@gmail.com>
parents: 17744
diff changeset
841
49961d67e4b9 Add new matrix functions (isdiag, isbanded, istril, istriu) (bug #42688).
Massimiliano Fasi <massimiliano.fasi@gmail.com>
parents: 17744
diff changeset
842 @DOCSTRING(isdiag)
49961d67e4b9 Add new matrix functions (isdiag, isbanded, istril, istriu) (bug #42688).
Massimiliano Fasi <massimiliano.fasi@gmail.com>
parents: 17744
diff changeset
843
49961d67e4b9 Add new matrix functions (isdiag, isbanded, istril, istriu) (bug #42688).
Massimiliano Fasi <massimiliano.fasi@gmail.com>
parents: 17744
diff changeset
844 @DOCSTRING(istril)
49961d67e4b9 Add new matrix functions (isdiag, isbanded, istril, istriu) (bug #42688).
Massimiliano Fasi <massimiliano.fasi@gmail.com>
parents: 17744
diff changeset
845
49961d67e4b9 Add new matrix functions (isdiag, isbanded, istril, istriu) (bug #42688).
Massimiliano Fasi <massimiliano.fasi@gmail.com>
parents: 17744
diff changeset
846 @DOCSTRING(istriu)
6550
1b7a6061a05d [project @ 2007-04-20 07:40:26 by jwe]
jwe
parents: 6549
diff changeset
847
1b7a6061a05d [project @ 2007-04-20 07:40:26 by jwe]
jwe
parents: 6549
diff changeset
848 @DOCSTRING(isprime)
13017
aaf6fbb2512f doc: Add cross references to "status of variables" in sections for predicates
Jordi Gutiérrez Hermoso <jordigh@gmail.com>
parents: 12581
diff changeset
849
aaf6fbb2512f doc: Add cross references to "status of variables" in sections for predicates
Jordi Gutiérrez Hermoso <jordigh@gmail.com>
parents: 12581
diff changeset
850 If instead of knowing properties of variables, you wish to know which
aaf6fbb2512f doc: Add cross references to "status of variables" in sections for predicates
Jordi Gutiérrez Hermoso <jordigh@gmail.com>
parents: 12581
diff changeset
851 variables are defined and to gather other information about the
17097
e7a059a9a644 doc: Use XREF as anchor prefix in documentation for clearer results in Info viewer.
Rik <rik@octave.org>
parents: 16939
diff changeset
852 workspace itself, @pxref{Status of Variables}.