## Copyright (C) 2000, 2002, 2004, 2005, 2006, 2007, 2009 Paul Kienzle
## Copyright (C) 2008 Jaroslav Hajek
##
## 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} {} repmat (@var{A}, @var{m}, @var{n})
## @deftypefnx {Function File} {} repmat (@var{A}, [@var{m} @var{n}])
## @deftypefnx {Function File} {} repmat (@var{A}, [@var{m} @var{n} @var{p} @dots{}])
## Form a block matrix of size @var{m} by @var{n}, with a copy of matrix
## @var{A} as each element.  If @var{n} is not specified, form an 
## @var{m} by @var{m} block matrix.
## @end deftypefn

## Author: Paul Kienzle <pkienzle@kienzle.powernet.co.uk>
## Created: July 2000

function x = repmat (a, m, n)

  if (nargin < 2 || nargin > 3)
    print_usage ();
  endif

  if (nargin == 3)
    if (! (isscalar (m) && isscalar (n)))
      error ("repmat: with 3 arguments m and n must be scalar");
    endif
    idx = [m, n];
  else 
    if (isscalar (m))
      idx = [m, m];
      n = m;
    elseif (isvector (m) && length (m) > 1)
      ## Ensure that we have a row vector
      idx = m(:).';
    else
      error ("repmat: invalid dimensional argument");
    endif
  endif
  
  if (all (idx < 0))
    error ("repmat: invalid dimensions");
  else
    idx = max (idx, 0);
  endif

  if (numel (a) == 1)
    ## optimize the scalar fill case.
    x(1:prod (idx)) = a;
    x = reshape (x, idx);
  elseif (ndims (a) == 2 && length (idx) < 3)
    if (issparse (a))
      x = kron (ones (idx), a);
    else
      ## indexing is now faster, so we use it rather than kron.
      m = rows (a); n = columns (a);
      p = idx(1); q = idx(2);
      x = reshape (a, m, 1, n, 1);
      x = x(:, ones (1, p), :, ones (1, q));
      x = reshape (x, m*p, n*q);
    endif
  else
    aidx = size (a);
    ## ensure matching size
    idx(end+1:length (aidx)) = 1;
    aidx(end+1:length (idx)) = 1;
    ## create subscript array
    cidx = cell (2, length (aidx));
    for i = 1:length (aidx)
      cidx{1,i} = ':';
      cidx{2,i} = ones (1, idx (i));
    endfor
    aaidx = aidx;
    # add singleton dims
    aaidx(2,:) = 1;
    a = reshape (a, aaidx(:));
    x = reshape (a (cidx{:}), idx .* aidx);
  endif

endfunction

# Test various methods of providing size parameters
%!shared x
%! x = [1 2;3 4];
%!assert(repmat(x, [1 1]), repmat(x, 1));
%!assert(repmat(x, [3 3]), repmat(x, 3));
%!assert(repmat(x, [1 1]), repmat(x, 1, 1));
%!assert(repmat(x, [1 3]), repmat(x, 1, 3));
%!assert(repmat(x, [3 1]), repmat(x, 3, 1));
%!assert(repmat(x, [3 3]), repmat(x, 3, 3));

# Tests for numel==1 case:
%!shared x, r
%! x = [ 65 ];
%! r = kron(ones(2,2), x);
%!assert(r, repmat(x, [2 2]));
%!assert(char(r), repmat(char(x), [2 2]));
%!assert(int8(r), repmat(int8(x), [2 2]));

# Tests for ndims==2 case:
%!shared x, r
%! x = [ 65 66 67 ];
%! r = kron(ones(2,2), x);
%!assert(r, repmat(x, [2 2]));
%!assert(char(r), repmat(char(x), [2 2]));
%!assert(int8(r), repmat(int8(x), [2 2]));

# Tests for dim>2 case:
%!shared x, r
%! x = [ 65 66 67 ];
%! r = kron(ones(2,2), x);
%! r(:,:,2) = r(:,:,1);
%!assert(r, repmat(x, [2 2 2]));
%!assert(char(r), repmat(char(x), [2 2 2]));
%!assert(int8(r), repmat(int8(x), [2 2 2]));

# Test that sparsity is kept
%!assert(sparse(4,4), repmat(sparse(2,2),[2 2]));


%!assert (size (repmat (".", -1, 1)), [0, 1]);
%!assert (size (repmat (".", 1, -1)), [1, 0]);
%!error (size (repmat (".", -1, -1)));