# HG changeset patch
# User jwe
# Date 1133321211 0
# Node ID 71cfd8fedd5decb3d2caaa2f8380bfcbc958f4c1
# Parent  815926a781f6b9b7b789d6258ab72713521eed5d
[project @ 2005-11-30 03:26:50 by jwe]

diff --git a/scripts/ChangeLog b/scripts/ChangeLog
--- a/scripts/ChangeLog
+++ b/scripts/ChangeLog
@@ -1,4 +1,7 @@
-2005-11-26  William Poetra Yoga Hadisoeseno  <williampoetra@gmail.com>
+2005-11-23  William Poetra Yoga Hadisoeseno  <williampoetra@yahoo.com>
+
+	* general/blkdiag.m: Import from octave-forge.
+	Ignore empty matrices in the input.  Add tests.
 
 	* general/isequal.m, general/isequalwithequalnans.m:
 	New wrapper scripts for general/__isequal__.m.
diff --git a/scripts/general/blkdiag.m b/scripts/general/blkdiag.m
new file mode 100644
--- /dev/null
+++ b/scripts/general/blkdiag.m
@@ -0,0 +1,71 @@
+## Copyright (C) 2000 Daniel Calvelo
+##
+## This program 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 2 of the License, or
+## (at your option) any later version.
+##
+## This program 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 this program; if not, write to the Free Software
+## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} blkdiag (@var{a}, @var{b}, @var{c}, ...)
+## Build a block diagonal matrix from @var{a}, @var{b}, @var{c}, ... .
+## All the arguments must be numeric and are two-dimensional matrices or
+## scalars.
+## @end deftypefn
+##
+## @seealso{diag, horzcat, vertcat}
+
+## Author: Daniel Calvelo
+## Modified by: William Poetra Yoga Hadisoeseno
+
+function retval = blkdiag (varargin)
+
+  if (nargin < 1)
+    usage ("blkdiag (a, b, c, ...)");
+  endif
+
+  # isnumeric is not an option for cellfun
+  if (! all (cell2mat (cellfun (@isnumeric, varargin))))
+    error ("all of the arguments to blkdiag must be numeric");
+  endif
+
+  # ndims is, so it's used here for speed
+  # note: trailing singletons are automatically (correctly) ignored
+  if (! all (cellfun ("ndims", varargin) == 2))
+    error ("all of the arguments to blkdiag must be two-dimensional matrices");
+  endif
+
+  # ignore empty matrices
+  notempty = ! cellfun ("isempty", varargin);
+  varargin = varargin(notempty);
+
+  # size is, but it's a bit different from calling size directly
+  csz = cumsum ([0 0; (cell2mat (cellfun (@size, varargin')))], 1);
+  retval = zeros (csz(end,:));
+  for p = 1:(length (notempty(notempty)))
+    retval((csz(p,1)+1):csz(p+1,1),(csz(p,2)+1):csz(p+1,2)) = varargin{p};
+  endfor
+
+endfunction
+
+# regular tests
+%!assert(blkdiag(1,ones(2),1),[1,0,0,0;0,1,1,0;0,1,1,0;0,0,0,1])
+%!assert(blkdiag([1,2],[3,4],[5,6]),[1,2,0,0,0,0;0,0,3,4,0,0;0,0,0,0,5,6])
+%!assert(blkdiag([1,2],[3;4],[5,6]),[1,2,0,0,0;0,0,3,0,0;0,0,4,0,0;0,0,0,5,6])
+%!assert(blkdiag([1,2;3,4],[5,6,7]),[1,2,0,0,0;3,4,0,0,0;0,0,5,6,7])
+# tests involving empty matrices
+%!assert(blkdiag([],[],[]),[])
+%!assert(blkdiag([],[1,2;3,4],[],5,[]),[1,2,0;3,4,0;0,0,5])
+%!assert(blkdiag(zeros(1,0,1),[1,2,3],1,0,5,zeros(0,1,1)),[1,2,3,0,0,0;0,0,0,1,0,0;0,0,0,0,0,0;0,0,0,0,0,5]);
+# sanity checks
+%!test
+%! A = rand (round (rand (1, 2) * 10));
+%! assert (blkdiag (A), A);