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diff --git a/octave_packages/symbolic-1.1.0/sym2poly.m b/octave_packages/symbolic-1.1.0/sym2poly.m
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+## Copyright (C) 2003 Willem J. Atsma <watsma@users.sf.net>
+##
+## This program 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.
+##
+## This software 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 this software; see the file COPYING.  If not,
+## see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{c} =} sym2poly (@var{p}, @var{x})
+## Returns the coefficients of the symbolic polynomial expression @var{p}
+## as a vector. If there is only one free variable in @var{p} the
+## coefficient vector @var{c} is a plain numeric vector. If there is more
+## than one free variable in @var{p}, a second argument @var{x} specifies the
+## free variable and the function returns a cell vector of symbolic expressions.
+## The coefficients correspond to decreasing exponent of the free variable.
+##
+## Example:
+## @example
+## symbols
+## x = sym("x");
+## y = sym("y");
+## c = sym2poly (x^2+3*x-4);    # c = [1,3,-4]
+## c = sym2poly (x^2+y*x,x);    # c = @{2,y,0@}
+## @end example
+##
+## If @var{p} is not a polynomial the result has no warranty.
+##
+## @seealso{poly2sym,polyval,roots}
+## @end deftypefn
+
+## Created: 18 April 2003
+## Changed: 25 April 2003
+##    Removed the use of differentiate to get to coefficients - round-off
+##     errors cause problems. Now using newly created sumterms().
+## Changed: 6 May 2003
+##    Removed the attempt to use ldegree(), degree() and coeff() - results
+##     with these are inconsistent.
+
+function c = sym2poly(p,x)
+
+  BADPOLY_COEFF_LIMIT = 500;
+
+  if is_vpa(p)
+    ## polynomial is one vpa number
+    c = to_double(p);
+    if length(c)!=1
+      error("Argument is not a polynomial.");
+    endif
+    return
+  endif
+
+  if !is_ex(p)
+    error("Argument has to be a symbolic expression.")
+  endif
+
+  pvars = findsymbols(p);
+  if isempty(pvars)
+    ## It is possible that we get an expression without any symbols.
+    c = to_double(p);
+    return;
+  endif
+  nvars = length(pvars); 
+
+  if nvars>1 && exist("x")!=1
+    error("Symbolic expression has more than 1 free variable; no variable specified.")
+  elseif exist("x")!=1
+    x = pvars{1};
+  endif
+
+  p = expand(p);
+
+  ## GiNaC has commands to access coefficients directly, but in octave this often
+  ## does not work, because for example x^2 typed in octave results in a 
+  ## non-integer power in GiNaC: x^2.0 .
+
+  [num,den] = numden(p);
+  tmp = findsymbols(den);
+  for i=1:length(tmp)
+    if tmp{i}==x
+      error("Symbolic expression is a ratio of polynomials.")
+    endif
+  endfor
+
+  p = expand(p);
+  p_terms = sumterms(p);
+  ## if this is well behaved, I can find the coefficients by dividing with x
+  c_ex = cell;
+  for i=1:length(p_terms)
+    tmp = p_terms{i};
+    for j=1:BADPOLY_COEFF_LIMIT
+      if disp(differentiate(tmp,x))=="0"
+        break;
+      endif
+      tmp = tmp/x;
+    endfor
+    if j==BADPOLY_COEFF_LIMIT
+      printf("Please examine your code or adjust this function.\n");
+      printf("This error may occur because the passed expression is not a polynomial.\n");
+      error("Reached the set limit (%d) for the number of coefficients.",BADPOLY_COEFF_LIMIT)
+    endif
+    if (length(c_ex)<j) || isempty(c_ex{j})
+      c_ex(j)=tmp;
+    else
+      c_ex(j) = c_ex{j}+tmp;
+    endif
+  endfor
+  order = length(c_ex)-1;
+
+  all_numeric = true;
+  for i=1:(order+1)
+    if isempty(c_ex{i})
+      c_ex(i) = vpa(0);
+    endif
+    cvar=findsymbols(c_ex{i});
+    ncvar = length(cvar);
+    if ncvar
+      all_numeric=false;
+      for j=1:ncvar
+        if disp(cvar{j})==disp(x)
+          printf("Possibly this error occurs because two symbols with the same name\n");
+          printf("are different to GiNaC. Make sure the free variable exists as a\n");
+          printf("symbol in your workspace.\n");
+          error("The symbolic expression is not a polynomial.")
+        endif
+      endfor
+    endif
+  endfor
+
+  c_ex = reverse(c_ex);
+
+  if all_numeric
+    for i=1:(order+1)
+      c(1,i)=to_double(c_ex{i});
+    endfor
+  else
+    c = c_ex;
+  endif
+
+endfunction
+
+%!shared
+% symbols
+% x=sym("x"); y=sym("y");
+%!test
+% assert(sym2poly (x^2+3*x-4), [1,3,-4]);
+%!test
+% assert (sym2poly (x^2+y*x,x), {2,y,0})