VECROTY: Transformation matrix for a rotation around the y axis. 
 
 Calling Sequence:
 
   ry = vecroty(angle);
 
 INPUT:
 
   angle		: rotation angle defined in radians
 
 OUTPUT:

   ry		: (4x4) Transformation matrix.
 
 
 Description:
 
   Return the (4x4) Transformation matrix for a rotation about the y axis
   by the defined angle.
 
   The matrix is:
 
         [  cos(angle)       0        sin(angle)       0]
         [      0            1            0            0]
         [ -sin(angle)       0        cos(angle)       0]
         [      0            0            0            1]
 
 Examples:
 
    Rotate the NURBS line (0.0 0.0 0.0) - (3.0 3.0 3.0) by 45 degrees
    around the y-axis
 
    line = nrbline([0.0 0.0 0.0],[3.0 3.0 3.0]);
    trans = vecroty(%pi/4);
    rline = nrbtform(line, trans);
 
 See also:
 
    nrbtform

    Copyright (C) 2000 Mark Spink

    This program 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.

Package: nurbs