--- /dev/null
+## Copyright (C) 2010 VZLU Prague
+##
+## 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 3 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 Octave; see the file COPYING. If not, see
+## <http://www.gnu.org/licenses/>.
+
+function s = plus (s1, s2)
+ if (isa (s1, "blksparse") && isa (s2, "blksparse"))
+ ## Conformance check.
+ siz1 = s1.siz;
+ bsiz1 = s1.bsiz;
+ siz2 = s2.siz;
+ bsiz2 = s2.bsiz;
+ if (bsiz1(2) != bsiz2(1))
+ gripe_nonconformant (bsiz1, bsiz2, "block sizes");
+ elseif (siz1(2) != siz2(1))
+ gripe_nonconformant (bsiz1.*siz1, bsiz2.*siz2);
+ endif
+
+ ## Stupid & simple.
+ s = blksparse ([s1.i; s2.i], [s1.j; s2.j], cat (3, s1.sv, s2.sv), siz1(1), siz1(2));
+ else
+ error ("blksparse: only blksparse + blksparse implemented");
+ endif
+endfunction
+
+function gripe_nonconformant (s1, s2, what = "arguments")
+ error ("Octave:nonconformant-args", ...
+ "nonconformant %s (op1 is %dx%d, op2 is %dx%d)", what, s1, s2);
+endfunction