RANDOMANGLE3D Return a 3D angle uniformly distributed on unit sphere.

   usage
   [THETA PHI] = randomAngle3d
   Generate an angle unformly distributed on the surface of the unit
   sphere.

   "Mathematical" convention is used: theta is the colatitude (angle with
   vertical axis, 0 for north pole, +pi for south pole, pi/2 for points at
   equator) with z=0. 
   phi is the same as matlab cart2sph: angle from Ox axis, counted
   positively counter-clockwise.

   [THETA PHI] = randomAngle3d(N)
   generates N random angles (N is a scalar). The result is a N-by-2
   array.

   Example:
     % Draw some points on the surface of a sphere
     figure;
     drawSphere; hold on;
     drawPoint3d(pts, '.');
     axis equal;

   See also:
   angles3d, sph2cart2, cart2sph2

 ------
 Author: David Legland
 e-mail: david.legland@grignon.inra.fr
 created the 18/02/2005.
 Copyright INRA - Cepia Software platform

Package: matgeom