/usr/share/octave/packages/linear-algebra-2.2.0/@blksparse/subsref.m is in octave-linear-algebra 2.2.0-1build1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 | ## 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 ss = subsref (s, subs)
if (length (subs) != 1)
error ("blksparse: invalid index chain");
endif
if (strcmp (subs(1).type, "()"))
ind = subs(1).subs;
if (length (ind) == 2)
idx = make_block_index (ind{1}, s.bsiz(1));
jdx = make_block_index (ind{2}, s.bsiz(2));
## Use sparse indexing to solve it all.
sn = sparse (s.i, s.j, 1:size (s.sv, 3), s.siz(1), s.siz (2));
sn = sn(idx, jdx);
[i, j, k] = find (sn);
ss = s;
ss.i = i;
ss.j = j;
ss.sv = s.sv(:,:,k);
ss.siz = size (sn);
else
error ("blksparse: linear indexing is not supported");
endif
else
error ("blksparse: only supports () indexing");
endif
endfunction
function bi = make_block_index (i, bs)
if (strcmp (i, ':'))
bi = i;
else
if (rem (numel (i), bs) == 0)
ba = reshape (i, bs, []);
bi = ba(1,:);
if (any (rem (bi, bs) != 1) || any ((ba != bsxfun (@plus, bi, [0:bs-1].'))(:)))
error ("blksparse: index must preserve block structure");
else
bi = ceil (bi / bs);
endif
else
error ("blksparse: index must preserve block structure");
endif
endif
endfunction
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