Mercurial > octave-antonio
annotate doc/interpreter/data.txi @ 8817:03b7f618ab3d
include docstrings for new functions in the manual
| author | John W. Eaton <jwe@octave.org> |
|---|---|
| date | Thu, 19 Feb 2009 15:39:19 -0500 |
| parents | fd42779a8428 |
| children | eb63fbe60fab |
| rev | line source |
|---|---|
| 6778 | 1 @c Copyright (C) 1996, 1997, 2007 John W. Eaton |
| 7018 | 2 @c |
| 3 @c This file is part of Octave. | |
| 4 @c | |
| 5 @c Octave is free software; you can redistribute it and/or modify it | |
| 6 @c under the terms of the GNU General Public License as published by the | |
| 7 @c Free Software Foundation; either version 3 of the License, or (at | |
| 8 @c your option) any later version. | |
| 9 @c | |
| 10 @c Octave is distributed in the hope that it will be useful, but WITHOUT | |
| 11 @c ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 12 @c FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 13 @c for more details. | |
| 14 @c | |
| 15 @c You should have received a copy of the GNU General Public License | |
| 16 @c along with Octave; see the file COPYING. If not, see | |
| 17 @c <http://www.gnu.org/licenses/>. | |
| 3294 | 18 |
| 4167 | 19 @node Data Types |
| 3294 | 20 @chapter Data Types |
| 21 @cindex data types | |
| 22 | |
| 23 All versions of Octave include a number of built-in data types, | |
| 6620 | 24 including real and complex scalars and matrices, character strings, |
| 25 a data structure type, and an array that can contain all data types. | |
| 3294 | 26 |
| 27 It is also possible to define new specialized data types by writing a | |
| 28 small amount of C++ code. On some systems, new data types can be loaded | |
| 29 dynamically while Octave is running, so it is not necessary to recompile | |
| 30 all of Octave just to add a new type. @xref{Dynamically Linked | |
| 3402 | 31 Functions}, for more information about Octave's dynamic linking |
| 3294 | 32 capabilities. @ref{User-defined Data Types} describes what you must do |
| 33 to define a new data type for Octave. | |
| 34 | |
| 3428 | 35 @DOCSTRING(typeinfo) |
| 36 | |
| 3294 | 37 @menu |
| 38 * Built-in Data Types:: | |
| 39 * User-defined Data Types:: | |
| 40 * Object Sizes:: | |
| 41 @end menu | |
| 42 | |
| 4167 | 43 @node Built-in Data Types |
| 3294 | 44 @section Built-in Data Types |
| 45 @cindex data types, built-in | |
| 46 @cindex built-in data types | |
| 47 | |
| 48 The standard built-in data types are real and complex scalars and | |
| 6620 | 49 matrices, ranges, character strings, a data structure type, and cell |
| 50 arrays. Additional built-in data types may be added in future versions. | |
| 51 If you need a specialized data type that is not currently provided as a | |
| 3294 | 52 built-in type, you are encouraged to write your own user-defined data |
| 53 type and contribute it for distribution in a future release of Octave. | |
| 54 | |
| 6620 | 55 The data type of a variable can be determined and changed through the |
| 56 use of the following functions. | |
| 57 | |
| 6550 | 58 @DOCSTRING(class) |
| 59 | |
| 60 @DOCSTRING(isa) | |
| 61 | |
| 62 @DOCSTRING(cast) | |
| 63 | |
| 6868 | 64 @DOCSTRING(typecast) |
| 65 | |
| 66 @DOCSTRING(swapbytes) | |
| 67 | |
| 3294 | 68 @menu |
| 69 * Numeric Objects:: | |
| 4169 | 70 * Missing Data:: |
| 3294 | 71 * String Objects:: |
| 72 * Data Structure Objects:: | |
| 6624 | 73 * Cell Array Objects:: |
| 3294 | 74 @end menu |
| 75 | |
| 4167 | 76 @node Numeric Objects |
| 3294 | 77 @subsection Numeric Objects |
| 78 @cindex numeric constant | |
| 79 @cindex numeric value | |
| 80 | |
| 6620 | 81 Octave's built-in numeric objects include real, complex, and integer |
| 82 scalars and matrices. All built-in floating point numeric data is | |
| 83 currently stored as double precision numbers. On systems that use the | |
| 84 IEEE floating point format, values in the range of approximately | |
| 3294 | 85 @iftex |
| 86 @tex | |
| 87 $2.2251\times10^{-308}$ to $1.7977\times10^{308}$ | |
| 88 @end tex | |
| 89 @end iftex | |
| 6620 | 90 @ifnottex |
| 3294 | 91 2.2251e-308 to 1.7977e+308 |
| 6620 | 92 @end ifnottex |
| 3294 | 93 can be stored, and the relative precision is approximately |
| 94 @iftex | |
| 95 @tex | |
| 96 $2.2204\times10^{-16}$. | |
| 97 @end tex | |
| 98 @end iftex | |
| 6620 | 99 @ifnottex |
| 3294 | 100 2.2204e-16. |
| 6620 | 101 @end ifnottex |
| 3294 | 102 The exact values are given by the variables @code{realmin}, |
| 103 @code{realmax}, and @code{eps}, respectively. | |
| 104 | |
| 105 Matrix objects can be of any size, and can be dynamically reshaped and | |
| 106 resized. It is easy to extract individual rows, columns, or submatrices | |
| 107 using a variety of powerful indexing features. @xref{Index Expressions}. | |
| 108 | |
| 109 @xref{Numeric Data Types}, for more information. | |
| 110 | |
| 4169 | 111 @node Missing Data |
| 112 @subsection Missing Data | |
| 113 @cindex missing data | |
| 114 | |
| 6620 | 115 It is possible to represent missing data explicitly in Octave using |
| 116 @code{NA} (short for ``Not Available''). Missing data can only be | |
| 117 represented when data is represented as floating point numbers. In this | |
| 118 case missing data is represented as a special case of the representation | |
| 119 of @code{NaN}. | |
| 120 | |
| 4169 | 121 @DOCSTRING(NA) |
| 122 | |
| 123 @DOCSTRING(isna) | |
| 124 | |
| 4167 | 125 @node String Objects |
| 3294 | 126 @subsection String Objects |
| 127 @cindex strings | |
| 128 @cindex character strings | |
| 129 @opindex " | |
| 130 @opindex ' | |
| 131 | |
| 132 A character string in Octave consists of a sequence of characters | |
| 133 enclosed in either double-quote or single-quote marks. Internally, | |
| 134 Octave currently stores strings as matrices of characters. All the | |
| 135 indexing operations that work for matrix objects also work for strings. | |
| 136 | |
| 137 @xref{Strings}, for more information. | |
| 138 | |
| 4167 | 139 @node Data Structure Objects |
| 3294 | 140 @subsection Data Structure Objects |
| 141 @cindex structures | |
| 142 @cindex data structures | |
| 143 | |
| 144 Octave's data structure type can help you to organize related objects of | |
| 145 different types. The current implementation uses an associative array | |
| 146 with indices limited to strings, but the syntax is more like C-style | |
| 147 structures. | |
| 148 | |
| 149 @xref{Data Structures}, for more information. | |
| 150 | |
| 6620 | 151 @node Cell Array Objects |
| 152 @subsection Cell Array Objects | |
| 153 @cindex cell arrays | |
| 154 | |
| 155 A Cell Array in Octave is general array that can hold any number of | |
| 156 different data types. | |
| 157 | |
| 158 @xref{Cell Arrays}, for more information. | |
| 159 | |
| 4167 | 160 @node User-defined Data Types |
| 3294 | 161 @section User-defined Data Types |
| 162 @cindex user-defined data types | |
| 163 @cindex data types, user-defined | |
| 164 | |
| 165 Someday I hope to expand this to include a complete description of | |
| 166 Octave's mechanism for managing user-defined data types. Until this | |
| 167 feature is documented here, you will have to make do by reading the code | |
| 168 in the @file{ov.h}, @file{ops.h}, and related files from Octave's | |
| 169 @file{src} directory. | |
| 170 | |
| 4167 | 171 @node Object Sizes |
| 3294 | 172 @section Object Sizes |
| 173 | |
| 174 The following functions allow you to determine the size of a variable or | |
| 175 expression. These functions are defined for all objects. They return | |
| 176 @minus{}1 when the operation doesn't make sense. For example, Octave's | |
| 177 data structure type doesn't have rows or columns, so the @code{rows} and | |
| 178 @code{columns} functions return @minus{}1 for structure arguments. | |
| 179 | |
| 6549 | 180 @DOCSTRING(ndims) |
| 181 | |
| 3373 | 182 @DOCSTRING(columns) |
| 3294 | 183 |
| 3373 | 184 @DOCSTRING(rows) |
| 3294 | 185 |
| 6549 | 186 @DOCSTRING(numel) |
| 187 | |
| 3373 | 188 @DOCSTRING(length) |
| 3294 | 189 |
| 3373 | 190 @DOCSTRING(size) |
| 3294 | 191 |
| 3373 | 192 @DOCSTRING(isempty) |
| 3294 | 193 |
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8817
03b7f618ab3d
include docstrings for new functions in the manual
John W. Eaton <jwe@octave.org>
parents:
7018
diff
changeset
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194 @DOCSTRING(isnull) |
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03b7f618ab3d
include docstrings for new functions in the manual
John W. Eaton <jwe@octave.org>
parents:
7018
diff
changeset
|
195 |
| 6549 | 196 @DOCSTRING(sizeof) |
| 197 | |
| 198 @DOCSTRING(size_equal) | |
| 6550 | 199 |
| 200 @DOCSTRING(squeeze) |