update packages

[CreaPhase.git] / octave_packages / m / general / randi.m

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+## Copyright (C) 2010-2012 Rik Wehbring
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or (at
+## your option) any later version.
+##
+## Octave is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+## General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn  {Function File} {} randi (@var{imax})
+## @deftypefnx {Function File} {} randi (@var{imax}, @var{n})
+## @deftypefnx {Function File} {} randi (@var{imax}, @var{m}, @var{n}, @dots{})
+## @deftypefnx {Function File} {} randi ([@var{imin} @var{imax}], @dots{})
+## @deftypefnx {Function File} {} randi (@dots{}, "@var{class}")
+## Return random integers in the range 1:@var{imax}.
+##
+## Additional arguments determine the shape of the return matrix.  When no
+## arguments are specified a single random integer is returned.  If one
+## argument @var{n} is specified then a square matrix @w{(@var{n} x @var{n})} is
+## returned.  Two or more arguments will return a multi-dimensional
+## matrix @w{(@var{m} x @var{n} x @dots{})}.
+##
+## The integer range may optionally be described by a two element matrix
+## with a lower and upper bound in which case the returned integers will be
+## on the interval @w{[@var{imin}, @var{imax}]}.
+##
+## The optional argument "@var{class}" will return a matrix of the requested
+## type.  The default is "double".
+##
+## The following example returns 150 integers in the range 1-10.
+##
+## @example
+## ri = randi (10, 150, 1)
+## @end example
+##
+## Implementation Note: @code{randi} relies internally on @code{rand} which
+## uses class "double" to represent numbers.  This limits the maximum
+## integer (@var{imax}) and range (@var{imax} - @var{imin}) to the value
+## returned by the @code{bitmax} function.  For IEEE floating point numbers
+## this value is @w{@math{2^{53} - 1}}.
+##
+## @seealso{rand}
+## @end deftypefn
+
+## Author: Rik Wehbring
+
+function ri = randi (bounds, varargin)
+
+  if (nargin < 1)
+    print_usage();
+  endif
+
+  if (! (isnumeric (bounds) && isreal (bounds)))
+    error ("randi: IMIN and IMAX must be real numeric bounds");
+  endif
+
+  if (isscalar (bounds))
+    imin = 1;
+    imax = fix (bounds);
+    if (imax < 1)
+      error ("randi: require IMAX >= 1");
+    endif
+  else
+    imin = fix (bounds(1));
+    imax = fix (bounds(2));
+    if (imax < imin)
+      error ("randi: require IMIN <= IMAX");
+    endif
+  endif
+
+  if (nargin > 1 && ischar (varargin{end}))
+    rclass = varargin{end};
+    varargin(end) = [];
+  else
+    rclass = "double";
+  endif
+
+  if (strfind (rclass, "int"))
+    if (imax > intmax (rclass))
+      error ("randi: require IMAX < intmax (CLASS)");
+    endif
+  elseif (strcmp (rclass, "single"))
+    if (imax > bitmax (rclass))
+      error ("randi: require IMAX < bitmax (CLASS)");
+    endif
+  endif
+  ## Limit set by use of class double in rand()
+  if (imax > bitmax)
+    error ("randi: maximum integer IMAX must be smaller than bitmax ()");
+  endif
+  if ((imax - imin) > bitmax)
+    error ("randi: maximum integer range must be smaller than bitmax ()");
+  endif
+
+
+  ri = imin + floor ( (imax-imin+1)*rand (varargin{:}) );
+
+  if (! strcmp (rclass, "double"))
+    ri = cast (ri, rclass);
+  endif
+
+endfunction
+
+%!test
+%! ri = randi (10, 1000, 1);
+%! assert(isequal(ri, fix (ri)));
+%! assert(min(ri) == 1);
+%! assert(max(ri) == 10);
+%! assert(rows(ri) == 1000);
+%! assert(columns(ri) == 1);
+%! assert(strcmp (class (ri), "double"));
+%!test
+%! ri = randi ([-5, 10], 1000, 1, "int8");
+%! assert(isequal(ri, fix (ri)));
+%! assert(min(ri) == -5);
+%! assert(max(ri) == 10);
+%! assert(strcmp (class (ri), "int8"));
+%!
+%!assert(size (randi(10, 3,1,2)) == [3, 1, 2])
+
+%% Test input validation
+%!error(randi())
+%!error(randi("test"))
+%!error(randi(10+2i))
+%!error(randi(0))
+%!error(randi([10, 1]))
+%!error(randi(256, "uint8"))
+%!error(randi(2^25, "single"))
+%!error(randi(bitmax() + 1))
+%!error(randi([-1, bitmax()]))
+