--- /dev/null
+## Copyright (C) 2012 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 -*-
+## Conjugate transpose of SS models.
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: May 2012
+## Version: 0.1
+
+function sys = __ctranspose__ (sys, ct)
+
+ a = sys.a;
+ b = sys.b;
+ c = sys.c;
+ d = sys.d;
+ e = sys.e;
+
+ if (ct) # continuous-time
+ sys.a = -a.';
+ sys.b = -c.';
+ sys.c = b.';
+ sys.d = d.';
+ sys.e = e.';
+ sys.stname = repmat ({""}, rows (a), 1);
+ else # discrete-time
+ [n, m] = size (b);
+ p = rows (c);
+ if (isempty (e))
+ e = eye (n);
+ endif
+ sys.a = blkdiag (e.', eye (p));
+ sys.b = [zeros(n, p); -eye(p)];
+ sys.c = [b.', zeros(m, p)];
+ sys.d = d.';
+ sys.e = [a.', c.'; zeros(p, n+p)];
+ sys.stname = repmat ({""}, n+p, 1);
+ endif
+
+endfunction