Use in-place operators in m-files where possible. * scripts/audio/@audioplayer/set.m, scripts/audio/@audiorecorder/set.m, scripts/audio/mu2lin.m, scripts/elfun/cosd.m, scripts/general/del2.m, scripts/general/profexplore.m, scripts/general/quadl.m, scripts/general/rat.m, scripts/general/rotdim.m, scripts/help/get_first_help_sentence.m, scripts/help/private/__strip_html_tags__.m, scripts/image/cubehelix.m, scripts/io/textread.m, scripts/linear-algebra/duplication_matrix.m, scripts/linear-algebra/housh.m, scripts/linear-algebra/krylov.m, scripts/linear-algebra/logm.m, scripts/linear-algebra/normest.m, scripts/linear-algebra/onenormest.m, scripts/optimization/fminsearch.m, scripts/optimization/lsqnonneg.m, scripts/optimization/qp.m, scripts/plot/appearance/annotation.m, scripts/plot/appearance/axis.m, scripts/plot/appearance/legend.m, scripts/plot/appearance/specular.m, scripts/plot/draw/colorbar.m, scripts/plot/draw/hist.m, scripts/plot/draw/plotmatrix.m, scripts/plot/draw/private/__stem__.m, scripts/plot/util/__actual_axis_position__.m, scripts/plot/util/__gnuplot_drawnow__.m, scripts/plot/util/findobj.m, scripts/plot/util/print.m, scripts/plot/util/private/__go_draw_axes__.m, scripts/plot/util/private/__print_parse_opts__.m, scripts/plot/util/rotate.m, scripts/polynomial/pchip.m, scripts/polynomial/polyaffine.m, scripts/polynomial/polyder.m, scripts/polynomial/private/__splinefit__.m, scripts/polynomial/residue.m, scripts/signal/arch_fit.m, scripts/signal/arch_rnd.m, scripts/signal/bartlett.m, scripts/signal/blackman.m, scripts/signal/freqz.m, scripts/signal/hamming.m, scripts/signal/hanning.m, scripts/signal/spectral_adf.m, scripts/signal/spectral_xdf.m, scripts/signal/stft.m, scripts/sparse/bicgstab.m, scripts/sparse/cgs.m, scripts/sparse/private/__sprand_impl__.m, scripts/sparse/qmr.m, scripts/sparse/sprandsym.m, scripts/sparse/svds.m, scripts/specfun/legendre.m, scripts/special-matrix/gallery.m, scripts/statistics/base/gls.m, scripts/statistics/models/logistic_regression.m, scripts/statistics/tests/kruskal_wallis_test.m, scripts/statistics/tests/manova.m, scripts/statistics/tests/wilcoxon_test.m, scripts/time/datevec.m: Use in-place operators in m-files where possible.

## Copyright (C) 1998-2015 Andy Adler
##
## 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} {} spy (@var{x})
## @deftypefnx {Function File} {} spy (@dots{}, @var{markersize})
## @deftypefnx {Function File} {} spy (@dots{}, @var{line_spec})
## Plot the sparsity pattern of the sparse matrix @var{x}.
##
## If the argument @var{markersize} is given as a scalar value, it is used to
## determine the point size in the plot.
##
## If the string @var{line_spec} is given it is passed to @code{plot} and
## determines the appearance of the plot.
## @seealso{plot, gplot}
## @end deftypefn

function spy (x, varargin)

  if (nargin < 1)
    print_usage ();
  endif

  markersize = NaN;
  if (nnz (x) < 1000)
    line_spec = "*";
  else
    line_spec = ".";
  endif
  for i = 1:length (varargin)
    if (ischar (varargin{i}))
      if (length (varargin{i}) == 1)
        line_spec = [line_spec, varargin{i}];
      else
        line_spec = varargin{i};
      endif
    elseif (isscalar (varargin{i}))
      markersize = varargin{i};
    else
      error ("spy: expected markersize or linespec");
    endif
  endfor

  [i, j, s] = find (x);
  [m, n] = size (x);

  if (isnan (markersize))
    plot (j, i, line_spec);
  else
    plot (j, i, line_spec, "markersize", markersize);
  endif

  axis ([0, n+1, 0, m+1], "ij");

endfunction


%!demo
%! clf;
%! spy (sprand (10,10, 0.2));

## Mark graphical function as tested by demo block
%!assert (1)