update packages

[CreaPhase.git] / octave_packages / m / general / sph2cart.m

diff --git a/octave_packages/m/general/sph2cart.m b/octave_packages/m/general/sph2cart.m
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+## Copyright (C) 2000-2012 Kai Habel
+##
+## 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{x}, @var{y}, @var{z}] =} sph2cart (@var{theta}, @var{phi}, @var{r})
+## @deftypefnx {Function File} {[@var{x}, @var{y}, @var{z}] =} sph2cart (@var{S})
+## @deftypefnx {Function File} {C =} sph2cart (@dots{})
+## Transform spherical to Cartesian coordinates.
+##
+## @var{theta} describes the angle relative to the positive x-axis.
+## @var{phi} is the angle relative to the xy-plane.
+## @var{r} is the distance to the origin @w{(0, 0, 0)}.
+## @var{theta}, @var{phi}, and @var{r} must be the same shape, or scalar.
+## If called with a single matrix argument then each row of @var{s}
+## represents the spherical coordinate (@var{theta}, @var{phi}, @var{r}).
+##
+## If only a single return argument is requested then return a matrix
+## @var{C} where each row represents one Cartesian coordinate
+## (@var{x}, @var{y}, @var{z}).
+## @seealso{cart2sph, pol2cart, cart2pol}
+## @end deftypefn
+
+## Author: Kai Habel <kai.habel@gmx.de>
+## Adapted-by: jwe
+
+function [x, y, z] = sph2cart (theta, phi, r)
+
+  if (nargin != 1 && nargin != 3)
+    print_usage ();
+  endif
+
+  if (nargin == 1)
+    if (ismatrix (theta) && columns (theta) == 3)
+      r = theta(:,3);
+      phi = theta(:,2);
+      theta = theta(:,1);
+    else
+      error ("sph2cart: matrix input must have 3 columns [THETA, PHI, R]");
+    endif
+  elseif (nargin == 3)
+    if (! ((ismatrix (theta) && ismatrix (phi) && ismatrix (r))
+            && (size_equal (theta, phi) || isscalar (theta) || isscalar (phi))
+            && (size_equal (theta, r) || isscalar (theta) || isscalar (r))
+            && (size_equal (phi, r) || isscalar (phi) || isscalar (r))))
+      error ("sph2cart: THETA, PHI, and R must be matrices of the same size, or scalar");
+    endif
+  endif
+
+  x = r .* cos (phi) .* cos (theta);
+  y = r .* cos (phi) .* sin (theta);
+  z = r .* sin (phi);
+
+  if (nargout <= 1)
+    x = [x, y, z];
+  endif
+
+endfunction
+
+%!test
+%! t = [0, 0, 0];
+%! p = [0, 0, 0];
+%! r = [0, 1, 2];
+%! [x, y, z] = sph2cart (t, p, r);
+%! assert (x, r);
+%! assert (y, [0, 0, 0]);
+%! assert (z, [0, 0, 0]);
+
+%!test
+%! t = 0;
+%! p = [0, 0, 0];
+%! r = [0, 1, 2];
+%! [x, y, z] = sph2cart (t, p, r);
+%! assert (x, r);
+%! assert (y, [0, 0, 0]);
+%! assert (z, [0, 0, 0]);
+
+%!test
+%! t = [0, 0, 0];
+%! p = 0;
+%! r = [0, 1, 2];
+%! [x, y, z] = sph2cart (t, p, r);
+%! assert (x, r);
+%! assert (y, [0, 0, 0]);
+%! assert (z, [0, 0, 0]);
+
+%!test
+%! t = [0, 0.5, 1]*pi;
+%! p = [0, 0, 0];
+%! r = 1;
+%! [x, y, z] = sph2cart (t, p, r);
+%! assert (x, [1, 0, -1], eps);
+%! assert (y, [0, 1, 0], eps);
+%! assert (z, [0, 0, 0], eps);
+
+%!test
+%! S = [ 0, 0, 1; 0.5*pi, 0, 1; pi, 0, 1];
+%! C = [ 1, 0, 0; 0, 1, 0; -1, 0, 0];
+%! assert (sph2cart(S), C, eps);
+