/usr/share/octave/packages/control-2.6.2/@lti/inv.m is in octave-control 2.6.2-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 | ## Copyright (C) 2009-2014 Lukas F. Reichlin
##
## This file is part of LTI Syncope.
##
## LTI Syncope 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.
##
## LTI Syncope 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 LTI Syncope. If not, see <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## Inversion of @acronym{LTI} objects.
## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
## Created: October 2009
## Version: 0.2
function retsys = inv (sys)
if (nargin != 1) # prevent sys = inv (sys1, sys2, sys3, ...)
error ("lti: inv: this is an unary operator");
endif
[p, m] = size (sys);
if (p != m)
error ("lti: inv: system must be square");
endif
retsys = __sys_inverse__ (sys);
## TODO: handle i/o names
endfunction
## inverse of state-space models
## test from SLICOT AB07ND
## result differs intentionally from a commercial
## implementation of an octave-like language
%!shared M, Me
%! A = [ 1.0 2.0 0.0
%! 4.0 -1.0 0.0
%! 0.0 0.0 1.0 ];
%!
%! B = [ 1.0 0.0
%! 0.0 1.0
%! 1.0 0.0 ];
%!
%! C = [ 0.0 1.0 -1.0
%! 0.0 0.0 1.0 ];
%!
%! D = [ 4.0 0.0
%! 0.0 1.0 ];
%!
%! sys = ss (A, B, C, D);
%! sysinv = inv (sys);
%! [Ai, Bi, Ci, Di] = ssdata (sysinv);
%! M = [Ai, Bi; Ci, Di];
%!
%! Ae = [ 1.0000 1.7500 0.2500
%! 4.0000 -1.0000 -1.0000
%! 0.0000 -0.2500 1.2500 ];
%!
%! Be = [-0.2500 0.0000
%! 0.0000 -1.0000
%! -0.2500 0.0000 ];
%!
%! Ce = [ 0.0000 0.2500 -0.2500
%! 0.0000 0.0000 1.0000 ];
%!
%! De = [ 0.2500 0.0000
%! 0.0000 1.0000 ];
%!
%! Me = [Ae, Be; Ce, De]; # Me = [Ae, -Be; -Ce, De];
%!
%!assert (M, Me, 1e-4);
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