ALGORITHM 752 - SRFPACK - SOFTWARE FOR SCATTERED DATA FITTING WITH A CONSTRAINED SURFACE UNDER TENSION

SRFPACK is a Fortran 77 software package that constructs a smooth inte rpolatory or approximating surface to data values associated with arbi trarily distributed points in the plane. It employs automatically sele cted tension factors to preserve shape properties of the data and to a void overshoot and undershoot associated with steep gradients. The dom ain of the fitting function may be nonconvex or multiply connected, an d the surface may he constrained to have discontinuous value or deriva tive across a user-specified curve representing, for example, a geolog ical fault line. Although triangle based, the method provides a means of avoiding the inaccuracy associated with long thin triangles on the boundary of the convex hull of the data abscissae.