A free form spline software package 1 |Documentation for version 1.1 |

This software package can be used to build spline surfaces of arbitrary topological shape. The resulting surfaces are of geometric continuity order 1 and bidegree 4 or 5 or of geometric continuity order 2 and bidegree 6 or 13. Keywords: G-splines, n-sided llings, n-sided patches. 1 The method This free form spline package can be used to construct G r-spline surfaces of bidegree 2r + 2 or 2r 2 +2r + 1, for r =1 � 2. Especially, it can be used to ll n-sided holes of a G r-surface for n =3 � 5 � 6 � 7 � 8. The general idea behind our free form splines is described in [Prautzsch '97] and [Prautzsch & Boehm '99, Chapter 14.4]. Here we only recall their properties, which are necessary and su cient towork with these splines. Every free form spline has an a nely invariant control net, i.e., an a ne image of the net controls the corresponding a ne image of the spline surface