NRBMULTIPATCH: construct the information for gluing conforming NURBS patches, using the same format as in GeoPDEs.
 
 Calling Sequence:
 
   [interfaces, boundary] = nrbmultipatch (nurbs, [tol]);
 
 INPUT:
 
   nurbs   : an array of NURBS surfaces or volumes (not both), see nrbmak.
   tol     : relative tolerance to compare knots and control points at the interfaces.
 
 OUTPUT: 
 
   interfaces: array with the information for each interface, that is:
      - number of the first patch (patch1), and the local side number (side1)
      - number of the second patch (patch2), and the local side number (side2)
      - flag (faces and volumes), ornt1, ornt2 (only volumes): information
        on how the two patches match, see below.
   boundary:   array with the boundary faces that do not belong to any interface
      - nsides:  total number of sides on the boundary array (numel(boundary))
      - patches: number of the patch to which the boundary belongs
      - sides:   number of the local side on the patch

 The faces of two patches must match conformingly: the control points must be the same,
  with the knot vectors (in each direction) related by an affine transformation.

 The boundary faces are stored separately, that is, nsides=1 for each boundary.
  To join several faces under the same condition, the user should do it by hand.
 
    Copyright (C) 2014, 2015, 2016, 2017 Rafael Vazquez

    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