doc: Update more docstrings to have one sentence summary as first line. Reviewed optimization, polynomial, signal script directories. * scripts/optimization/fminbnd.m, scripts/optimization/fminsearch.m, scripts/optimization/fminunc.m, scripts/optimization/fsolve.m, scripts/optimization/fzero.m, scripts/optimization/glpk.m, scripts/optimization/lsqnonneg.m, scripts/optimization/pqpnonneg.m, scripts/optimization/qp.m, scripts/optimization/sqp.m, scripts/polynomial/compan.m, scripts/polynomial/mkpp.m, scripts/polynomial/mpoles.m, scripts/polynomial/pchip.m, scripts/polynomial/poly.m, scripts/polynomial/polyaffine.m, scripts/polynomial/polyder.m, scripts/polynomial/polyeig.m, scripts/polynomial/polyfit.m, scripts/polynomial/polygcd.m, scripts/polynomial/polyint.m, scripts/polynomial/polyout.m, scripts/polynomial/polyval.m, scripts/polynomial/ppder.m, scripts/polynomial/ppint.m, scripts/polynomial/ppjumps.m, scripts/polynomial/ppval.m, scripts/polynomial/residue.m, scripts/polynomial/roots.m, scripts/polynomial/spline.m, scripts/polynomial/splinefit.m, scripts/polynomial/unmkpp.m, scripts/signal/arch_fit.m, scripts/signal/arch_rnd.m, scripts/signal/arma_rnd.m, scripts/signal/autoreg_matrix.m, scripts/signal/bartlett.m, scripts/signal/blackman.m, scripts/signal/detrend.m, scripts/signal/diffpara.m, scripts/signal/durbinlevinson.m, scripts/signal/fftconv.m, scripts/signal/fftfilt.m, scripts/signal/fftshift.m, scripts/signal/filter2.m, scripts/signal/freqz.m, scripts/signal/hamming.m, scripts/signal/hanning.m, scripts/signal/hurst.m, scripts/signal/ifftshift.m, scripts/signal/periodogram.m, scripts/signal/sinc.m, scripts/signal/sinetone.m, scripts/signal/sinewave.m, scripts/signal/spectral_adf.m, scripts/signal/spectral_xdf.m, scripts/signal/spencer.m, scripts/signal/stft.m, scripts/signal/synthesis.m, scripts/signal/unwrap.m, scripts/signal/yulewalker.m: Update more docstrings to have one sentence summary as first line.

## Copyright (C) 2008-2015 VZLU Prague, a.s., Czech Republic
##
## 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 3 of the License, 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, see
## <http://www.gnu.org/licenses/>.

## -*- texinfo -*-
## @deftypefn  {Function File} {@var{ppi} =} ppint (@var{pp})
## @deftypefnx {Function File} {@var{ppi} =} ppint (@var{pp}, @var{c})
## Compute the integral of the piecewise polynomial struct @var{pp}.
##
## @var{c}, if given, is the constant of integration.
## @seealso{mkpp, ppval, ppder}
## @end deftypefn

function ppi = ppint (pp, c)
  if (nargin < 1 || nargin > 2)
    print_usage ();
  endif
  if (! (isstruct (pp) && strcmp (pp.form, "pp")))
    error ("ppint: PP must be a structure");
  endif

  [x, p, n, k, d] = unmkpp (pp);
  p = reshape (p, [], k);

  ## Get piecewise antiderivatives
  pi = p / diag (k:-1:1);
  k += 1;
  if (nargin == 1)
    pi(:, k) = 0;
  else
    pi(:, k) = repmat (c(:), n, 1);
  endif

  ppi = mkpp (x, pi, d);

  tmp = -cumsum (ppjumps (ppi), length (d) + 1);
  ppi.coefs(prod (d)+1 : end, k) = tmp(:);

endfunction


%!shared x,y,pp,ppi
%! x = 0:8;
%! y = [ ones(size(x)); x+1 ];
%! pp = spline (x, y);
%! ppi = ppint (pp);
%!assert (ppval (ppi, x), [x; 0.5*x.^2 + x], 1e-14)
%!assert (ppi.order, 5)