  A new modification of the Hermite cubic rectangular patch is proposed: the
S-Patch, which is based on the requirement that diagonal curves must be of
degree 3 instead of degree 6 as it is in the case of the Hermite patch.
Theoretical derivation of conditions is presented and some experimental results
as well. The S-Patch is convenient for applications, where different
tessellation of the u-v domain is needed, boundary and diagonal curves of
different degrees are not acceptable.
