## Copyright (C) 2010 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{@code{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()]))