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########################################################################
##
## Copyright (C) 2007-2024 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
## 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
## <https://www.gnu.org/licenses/>.
##
########################################################################
## -*- texinfo -*-
## @deftypefn {} {} ellipsoid (@var{xc}, @var{yc}, @var{zc}, @var{xr}, @var{yr}, @var{zr})
## @deftypefnx {} {} ellipsoid (@dots{}, @var{n})
## @deftypefnx {} {} ellipsoid (@var{hax}, @dots{})
## @deftypefnx {} {[@var{x}, @var{y}, @var{z}] =} ellipsoid (@dots{})
## Plot a 3-D ellipsoid.
##
## The inputs @var{xc}, @var{yc}, @var{zc} specify the center of the ellipsoid.
## The inputs @var{xr}, @var{yr}, @var{zr} specify the semi-major axis lengths.
##
## The optional input @var{n} determines the number of faces around the
## circumference of the cylinder. The default value is 20.
##
## If the first argument @var{hax} is an axes handle, then plot into this axes,
## rather than the current axes returned by @code{gca}.
##
## If outputs are requested @code{ellipsoid} returns three matrices in
## @code{meshgrid} format, such that @code{surf (@var{x}, @var{y}, @var{z})}
## generates the ellipsoid.
## @seealso{cylinder, rectangle, sphere}
## @end deftypefn
function [x, y, z] = ellipsoid (varargin)
[hax, varargin, nargin] = __plt_get_axis_arg__ ("ellipsoid", varargin{:});
if (nargin != 6 && nargin != 7)
print_usage ();
endif
xc = varargin{1};
yc = varargin{2};
zc = varargin{3};
xr = varargin{4};
yr = varargin{5};
zr = varargin{6};
if (nargin == 6)
n = 20;
else
n = varargin{7};
if (! (isreal (n) && isscalar (n) && n > 0))
error ("ellipsoid: N must be a real scalar > 0");
endif
n = floor (n);
endif
theta = linspace (0, 2 * pi, n + 1);
phi = linspace (-pi / 2, pi / 2, n + 1);
[theta, phi] = meshgrid (theta, phi);
xx = xr .* cos (phi) .* cos (theta) + xc;
yy = yr .* cos (phi) .* sin (theta) + yc;
zz = zr .* sin (phi) + zc;
if (nargout > 0)
x = xx;
y = yy;
z = zz;
else
oldfig = [];
if (! isempty (hax))
oldfig = get (0, "currentfigure");
endif
unwind_protect
hax = newplot (hax);
surf (xx, yy, zz);
unwind_protect_cleanup
if (! isempty (oldfig))
set (0, "currentfigure", oldfig);
endif
end_unwind_protect
endif
endfunction
%!demo
%! clf;
%! ellipsoid (0, 0, 1, 2, 3, 4, 20);
%! title ("ellipsoid()");
%!test <*64468> # No return if nargout = 0
%! hf = figure ("visible", "off");
%! hax = gca ();
%! unwind_protect
%! 1 + 1;
%! assert (ans, 2);
%! ellipsoid (hax, 0, 0, 0, 1, 1, 1);
%! assert (ans, 2);
%!
%! unwind_protect_cleanup
%! close (hf);
%! end_unwind_protect
## Test input validation
%!error <Invalid call> ellipsoid (1,2,3,4,5)
%!error <Invalid call> ellipsoid (1,2,3,4,5,6,7,8)
%!error <N must be a real scalar> ellipsoid (1,2,3,4,5,6, 2i)
%!error <N must be a real scalar> ellipsoid (1,2,3,4,5,6, ones (2,2))
%!error <N must be a real scalar . 0> ellipsoid (1,2,3,4,5,6, -1)
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