## Copyright (C) 1994-2020 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this distribution
## or <https://octave.org/COPYRIGHT.html/>.
##
##
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## under the terms of the GNU General Public License as published by
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## -*- texinfo -*-
## @deftypefn {} {} polyreduce (@var{c})
## Reduce a polynomial coefficient vector to a minimum number of terms by
## stripping off any leading zeros.
## @seealso{polyout}
## @end deftypefn

## Author: Tony Richardson <arichard@stark.cc.oh.us>
## Created: June 1994
## Adapted-By: jwe

function p = polyreduce (c)

  if (nargin != 1)
    print_usage ();
  elseif (! isvector (c) || isempty (c))
    error ("polyreduce: C must be a non-empty vector");
  endif

  idx = find (c != 0, 1);

  if (isempty (idx))
    p = 0;
  else
    p = c(idx:end);
  endif

endfunction


%!assert (polyreduce ([0, 0, 1, 2, 3]), [1, 2, 3])
%!assert (polyreduce ([1, 2, 3, 0, 0]), [1, 2, 3, 0, 0])
%!assert (polyreduce ([1, 0, 3]), [1, 0, 3])
%!assert (polyreduce ([0, 0, 0]), 0)

%!error polyreduce ()
%!error polyreduce (1, 2)
%!error <C must be a non-empty vector> polyreduce ([1, 2; 3, 4])
%!error <C must be a non-empty vector> polyreduce ([])