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- # Copyright (C) 1993, 1994, 1995 John W. Eaton
- #
- # This file is part of Octave.
- #
- # Octave 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 2, or (at your option) any
- # later version.
- #
- # Octave 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, write to the Free
- # Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
-
- function retval = toeplitz (c, r)
-
- # usage: toeplitz (c, r)
- #
- # Return the Toeplitz matrix constructed given the first column
- # c, and (optionally) the first row r.
- #
- # If the second argument is omitted, the first row is taken to be the
- # same as the first column. If the first element of c is not the same
- # as the first element of r, the first element of c is used.
- #
- # See also: hankel, vander, hadamard, hilb, invhib
-
- if (nargin == 1)
- r = c;
- elseif (nargin != 2)
- usage ("toeplitz (c, r)");
- endif
-
- [c_nr, c_nc] = size (c);
- [r_nr, r_nc] = size (r);
-
- if ((c_nr != 1 && c_nc != 1) || (r_nr != 1 && r_nc != 1))
- error ("toeplitz: expecting vector arguments")
- endif
-
- if (c_nc != 1)
- c = c.';
- endif
-
- if (r_nr != 1)
- r = r.';
- endif
-
- if (r (1) != c (1))
- warning ("toeplitz: column wins diagonal conflict");
- endif
-
- # If we have a single complex argument, we want to return a
- # Hermitian-symmetric matrix (actually, this will really only be
- # Hermitian-symmetric if the first element of the vector is real).
-
- if (nargin == 1)
- c = conj (c);
- c(1) = conj (c(1));
- endif
-
- # This should probably be done with the colon operator...
-
- nc = length (r);
- nr = length (c);
-
- retval = zeros (nr, nc);
-
- for i = 1:min (nc, nr)
- retval (i:nr, i) = c (1:nr-i+1);
- endfor
-
- for i = 1:min (nr, nc-1)
- retval (i, i+1:nc) = r (2:nc-i+1);
- endfor
-
- endfunction
-