# Copyright (C) 1993, 1994, 1995 John W. Eaton
# 
# 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, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

function sombrero (n)

# usage: sombrero (n)
#
# Draw a `sombrero' in three dimensions using n grid lines.  The
# function plotted is
#
#   z = sin (x^2 + y^2) / (x^2 + y^2);

  if (nargin != 1)
    usage ("sombrero (n)");
  endif

  x = y = linspace (-8, 8, n)';
  [xx, yy] = meshdom (x, y);
  r = sqrt (xx .^ 2 + yy .^ 2) + eps;
  z = sin (r) ./ r;

  mesh (x, y, z);

endfunction