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annotate scripts/general/randi.m @ 10892:20ce631f0f12

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Add new randi function for random integers.
author Rik <octave@nomad.inbox5.com>
date Sun, 15 Aug 2010 13:50:41 -0700
parents
children 4a2dabfb078b
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10892
20ce631f0f12 Add new randi function for random integers.
Rik <octave@nomad.inbox5.com>
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1 ## Copyright (C) 2010 Rik Wehbring
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2 ##
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3 ## This file is part of Octave.
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4 ##
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5 ## Octave is free software; you can redistribute it and/or modify it
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6 ## under the terms of the GNU General Public License as published by
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7 ## the Free Software Foundation; either version 3 of the License, or (at
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8 ## your option) any later version.
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9 ##
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10 ## Octave is distributed in the hope that it will be useful, but
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 ## General Public License for more details.
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14 ##
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15 ## You should have received a copy of the GNU General Public License
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16 ## along with Octave; see the file COPYING. If not, see
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17 ## <http://www.gnu.org/licenses/>.
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18
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19 ## -*- texinfo -*-
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20 ## @deftypefn {Function File} {} randi (@var{imax})
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21 ## @deftypefnx {Function File} {} randi (@var{imax}, @var{n})
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22 ## @deftypefnx {Function File} {} randi (@var{imax}, @var{m}, @var{n}, @dots{})
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23 ## @deftypefnx {Function File} {} randi ([@var{imin}, @var{imax}], @dots{})
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24 ## @deftypefnx {Function File} {} randi (@dots{}, "@var{class}")
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25 ## Return random integers in the range 1:@var{imax}.
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26 ##
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27 ## Additional arguments determine the shape of the return matrix. When no
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28 ## arguments are specified a single random integer is returned. If one
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29 ## argument @var{n} is specified then a square matrix @w{(@var{n} x @var{n})} is
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30 ## returned. Two or more arguments will return a multi-dimensional
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31 ## matrix @w{(@var{m} x @var{n} x @dots{})}.
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32 ##
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33 ## The integer range may optionally be described by a two element matrix
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34 ## with a lower and upper bound in which case the returned integers will be
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35 ## on the interval @w{[@var{imin}, @var{imax}]}.
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36 ##
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37 ## The optional argument "@var{class}" will return a matrix of the requested
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38 ## type. The default is "double".
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39 ##
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40 ## The following example returns 150 integers in the range 1-10.
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41 ##
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42 ## @example
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43 ## ri = randi (10, 150, 1);
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44 ## @end example
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45 ##
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46 ## Implementation Note: @code{randi} relies internally on @code{rand} which
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47 ## uses class "double" to represent numbers. This limits the maximum
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48 ## integer (@var{imax}) and range (@var{imax} - @var{imin}) to the value
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49 ## returned by the @code{bitmax} function. For IEEE floating point numbers
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50 ## this value is @w{@code{2^53 - 1}}.
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51 ##
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52 ## @seealso{rand}
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53 ## @end deftypefn
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54
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55 ## Author: Rik Wehbring
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56
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57 function ri = randi (bounds, varargin)
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58
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59 if (nargin < 1)
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60 print_usage();
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61 endif
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62
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63 if (! (isnumeric (bounds) && isreal (bounds)))
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64 error ("randi: IMIN and IMAX must be real numeric bounds");
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65 endif
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66
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67 if (isscalar (bounds))
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68 imin = 1;
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69 imax = fix (bounds);
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70 if (imax < 1)
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71 error ("randi: require IMAX >= 1");
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72 endif
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73 else
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74 imin = fix (bounds(1));
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75 imax = fix (bounds(2));
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76 if (imax < imin)
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77 error ("randi: require IMIN <= IMAX");
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78 endif
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79 endif
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80
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81 if (nargin > 1 && ischar (varargin{end}))
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82 rclass = varargin{end};
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83 varargin(end) = [];
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84 else
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85 rclass = "double";
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86 endif
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87
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88 ## FIXME: No check for class "single"
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89 if (strfind (rclass, "int"))
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90 if (imax > intmax (rclass))
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91 error ("randi: require IMAX < intmax (CLASS)");
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92 endif
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93 endif
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94 ## Limit set by use of class double in rand()
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95 if (imax > bitmax)
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96 error ("randi: maximum integer IMAX must be smaller than bitmax ()");
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97 endif
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98 if ((imax - imin) > bitmax)
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99 error ("randi: maximum integer range must be smaller than bitmax ()");
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100 endif
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101
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102
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103 ri = imin + floor ( (imax-imin+1)*rand (varargin{:}) );
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104
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105 if (! strcmp (rclass, "double"))
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106 ri = cast (ri, rclass);
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107 endif
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108
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109 endfunction
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110
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111 %!test
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112 %! ri = randi (10, 1000, 1);
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113 %! assert(isequal(ri, fix (ri)));
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114 %! assert(min(ri) == 1);
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115 %! assert(max(ri) == 10);
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116 %! assert(rows(ri) == 1000);
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117 %! assert(columns(ri) == 1);
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118 %! assert(strcmp (class (ri), "double"));
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119 %!test
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120 %! ri = randi ([-5, 10], 1000, 1, "int8");
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121 %! assert(isequal(ri, fix (ri)));
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122 %! assert(min(ri) == -5);
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123 %! assert(max(ri) == 10);
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124 %! assert(strcmp (class (ri), "int8"));
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125 %!
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126 %!assert(size (randi(10, 3,1,2)) == [3, 1, 2])
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127
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128 %% Test input validation
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129 %!error(randi())
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130 %!error(randi("test"))
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131 %!error(randi(10+2i))
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132 %!error(randi(0))
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133 %!error(randi([10, 1]))
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134 %!error(randi(256, "uint8"))
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135 %!error(randi(bitmax() + 1))
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136 %!error(randi([-1, bitmax()]))
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137