# Copyright (C) 1995,1998 Auburn University.  All Rights Reserved.
#
# 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 y = polyout(c,x)
#
# usage: [y=] polyout(c[,x])
#
# print formatted polynomial 
#   c(x) = c(1) * x^n + ... + c(n) x + c(n+1)
# in a string or to the screen (if y is omitted)
# x defaults to the string "s"
#
#  SEE ALSO: polyval, polyvalm, poly, roots, conv, deconv, residue, 
#	filter, polyderiv, polyinteg

# Written by A. Scottedward Hodel (scotte@eng.auburn.edu) May 1995)
# Nov 1998: Correctly handles complex coefficients
  
  if (nargin < 1 ) || (nargin > 2) || (nargout < 0 ) || (nargout > 1)
    usage("[y = ] polyout(c,[x])");
  endif

  if (!is_vector(c))
    error("polyout: first argument must be a vector");
  endif
  
  if (nargin == 1)
    x = 's';
  elseif( ! isstr(x) )
    error("polyout: second argument must be a string");
  endif

  n = length(c);
  if(n > 0)
    n1 = n+1;

    if( imag(c(1)) )     tmp = com2str(c(1))
    else                 tmp = num2str(c(1));       endif

    for ii=2:n
      if(real(c(ii)) < 0)     ns = ' - ';    c(ii) = -c(ii);
      else                    ns = ' + ';                      endif

      if( imag(c(ii)) )       nstr = sprintf("(%s)",com2str(c(ii)) );
      else                    nstr = num2str(c(ii));           endif

      tmp = sprintf("%s*%s^%d%s%s",tmp,x,n1-ii,ns,nstr);
      
    endfor
  else
    tmp = " ";
  endif

  if(nargout == 0)
    disp(tmp)
  else
    y = tmp;
  endif

endfunction