--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FIXES/polyderiv.m	Wed Oct 10 19:54:49 2001 +0000
@@ -0,0 +1,93 @@
+## Copyright (C) 1996, 1997 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, 59 Temple Place - Suite 330, Boston, MA
+## 02111-1307, USA.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} polyderiv (@var{c})
+## @deftypefnx {Function File} {[@var{q}] =} polyder (@var{b}, @var{a})
+## @deftypefnx {Function File} {[@var{q}, @var{r}] =} polyder (@var{b}, @var{a})
+## Return the coefficients of the derivative of the polynomial whose
+## coefficients are given by vector @var{c}.  If a pair of polynomials
+## is given @var{b} and @var{a}, the derivative of the product is
+## returned in @var{q}, or the quotient numerator in @var{q} and the
+## quotient denominator in @var{r}.
+## @end deftypefn
+## @seealso{poly, polyinteg, polyreduce, roots, conv, deconv, residue,
+## filter, polygcd, polyval, and polyvalm}
+
+## Author: Tony Richardson <arichard@stark.cc.oh.us>
+## Created: June 1994
+## Adapted-By: jwe
+## Paul Kienzle <pkienzle@kienzle.powernet.co.uk>
+##    handle b/a and b*a
+
+function [q, r] = polyderiv (p, a)
+
+  if (nargin < 1 || nargin > 3)
+    usage ("q=polyderiv(p) or q=polyderiv(b,a) or [q, r]=polyderiv(b,a)");
+  endif
+
+  if (! is_vector (p))
+    error ("polyderiv: argument must be a vector");
+  endif
+
+  if (nargin == 2)
+    if (! is_vector (a))
+      error ("polyderiv: argument must be a vector");
+    endif
+    if (nargout == 1) 
+      ## derivative of p*a returns a single polynomial
+      q = polyderiv(conv(p,a));
+    else
+      ## derivative of p/a returns numerator and denominator
+      r = conv(a, a);
+      if length(p) == 1
+	q = -p * polyderiv(a);
+      elseif length(a) == 1
+	q = a * polyderiv(p);
+      else
+      	q = conv(polyderiv(p),a) - conv(p,polyderiv(a));
+      	q = polyreduce(q);
+      endif
+
+      ## remove common factors from numerator and denominator
+      x = polygcd(q,r);
+      if length(x)!=1
+      	q=deconv(q,x);
+      	r=deconv(r,x);
+      endif
+
+      ## move all the gain into the numerator
+      q=q/r(1);
+      r=r/r(1);
+    endif
+    return;
+  endif
+
+  lp = length (p);
+  if (lp == 1)
+    q = 0;
+    return;
+  elseif (lp == 0)
+    q = [];
+    return;
+  end
+
+  q = p (1:(lp-1)) .* [(lp-1):-1:1];
+
+endfunction