/usr/share/octave/packages/control-3.0.0/@tf/__sys_inverse__.m is in octave-control 3.0.0-2.
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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 | ## Copyright (C) 2009-2015 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 TF models.
## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
## Created: October 2009
## Version: 0.4
function sys = __sys_inverse__ (sys)
if (issiso (sys)) # SISO
num = sys.num;
den = sys.den;
if (num{1,1} == 0) # catch case num = 0
sys.num(1,1) = tfpoly (0);
sys.den(1,1) = tfpoly (1);
else
sys.num = den;
sys.den = num;
endif
else # MIMO
## I've calculated TF inversion of 2x2 and 3x3 systems with Sage CAS,
## but the formulae give systems with very high orders, therefore
## I always use the conversion to state-space and back.
[num, den] = tfdata (inv (ss (sys)), "tfpoly");
sys.num = num;
sys.den = den;
endif
endfunction
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