update packages

[CreaPhase.git] / octave_packages / m / plot / sombrero.m

diff --git a/octave_packages/m/plot/sombrero.m b/octave_packages/m/plot/sombrero.m
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+## Copyright (C) 1993-2012 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 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} {} sombrero (@var{n})
+## Produce the familiar three-dimensional sombrero plot using @var{n}
+## grid lines.  If @var{n} is omitted, a value of 41 is assumed.
+##
+## The function plotted is
+##
+## @example
+## z = sin (sqrt (x^2 + y^2)) / (sqrt (x^2 + y^2))
+## @end example
+## @seealso{surf, meshgrid, mesh}
+## @end deftypefn
+
+## Author: jwe
+
+function [x, y, z] = sombrero (n)
+
+  if (nargin == 0)
+    n = 41;
+  endif
+
+  if (nargin < 2)
+    if (n > 1)
+      tx = linspace (-8, 8, n)';
+      ty = tx;
+      [xx, yy] = meshgrid (tx, ty);
+      r = sqrt (xx .^ 2 + yy .^ 2) + eps;
+      tz = sin (r) ./ r;
+      if (nargout == 0)
+        surf (tx, ty, tz);
+        box ("off");
+      else
+        x = tx;
+        y = ty;
+        z = tz;
+      endif
+    else
+      error ("sombrero: number of grid lines must be greater than 1");
+    endif
+  else
+    print_usage ();
+  endif
+
+endfunction
+
+%!demo
+%! clf
+%! sombrero ();