# HG changeset patch
# User Jaroslav Hajek <highegg@gmail.com>
# Date 1238999593 -7200
# Node ID 38c3a0f8c6d0c58909700c48814d9d39f4f65a7d
# Parent  45c832e9976d763d93510398fb670b9293e6a9d0
optimize toeplitz

diff -r 45c832e9976d -r 38c3a0f8c6d0 scripts/ChangeLog
--- a/scripts/ChangeLog	Sun Apr 05 13:19:07 2009 -0400
+++ b/scripts/ChangeLog	Mon Apr 06 08:33:13 2009 +0200
@@ -1,3 +1,7 @@
+2009-04-06  Jaroslav Hajek  <highegg@gmail.com>
+
+	* special-matrix/toeplitz.m: Optimize.
+
 2008-04-03  David Bateman  <dbateman@free.fr>
 
 	* plot/__scatter__.m: correct indexing of cdata.x
diff -r 45c832e9976d -r 38c3a0f8c6d0 scripts/special-matrix/toeplitz.m
--- a/scripts/special-matrix/toeplitz.m	Sun Apr 05 13:19:07 2009 -0400
+++ b/scripts/special-matrix/toeplitz.m	Mon Apr 06 08:33:13 2009 +0200
@@ -1,5 +1,6 @@
 ## Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2004,
 ##               2005, 2006, 2007, 2008, 2009 John W. Eaton
+## Copyright (C) 2009 VZLU Prague
 ##
 ## This file is part of Octave.
 ##
@@ -54,7 +55,7 @@
 ## @seealso{hankel, vander, sylvester_matrix, hilb, invhilb}
 ## @end deftypefn
 
-## Author: jwe
+## Author: jwe && jh
 
 function retval = toeplitz (c, r)
 
@@ -64,19 +65,17 @@
     print_usage ();
   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))
+  if (! (isvector (c) && isvector (r)))
     error ("toeplitz: expecting vector arguments");
   endif
 
-  if (c_nc != 1)
-    c = c.';
-  endif
+  nc = length (r);
+  nr = length (c);
 
-  if (r_nr != 1)
-    r = r.';
+  if (nr == 0 || nc == 0)
+    ## Empty matrix.
+    retval = zeros (nr, nc, class (c));
+    return;
   endif
 
   if (r (1) != c (1))
@@ -87,25 +86,19 @@
   ## Hermitian-symmetric matrix (actually, this will really only be
   ## Hermitian-symmetric if the first element of the vector is real).
 
-  if (nargin == 1)
+  if (nargin == 1 && iscomplex (c))
     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 = resize (resize (c, 0), nr, nc);
+  ## Concatenate data into a single column vector.
+  data = [r(end:-1:2)(:); c(:)];
 
-  for i = 1:min (nc, nr)
-    retval (i:nr, i) = c (1:nr-i+1);
-  endfor
+  ## Get slices.
+  slices = cellslices (data, nc:-1:1, nc+nr-1:-1:nr);
 
-  for i = 1:min (nr, nc-1)
-    retval (i, i+1:nc) = r (2:nc-i+1);
-  endfor
+  ## Form matrix.
+  retval = horzcat (slices{:});
 
 endfunction