Algorithm 792: Accuracy tests of ACM algorithms for interpolation of scattered data in the plane

We present results of accuracy tests on scattered-data fitting methods that have been published as ACM algorithms. The algorithms include seven triangulation-based methods and three modified Shepard methods, two of which are new algorithms. Our purpose is twofold: to guide potential users in the selection of an appropriate algorithm and to provide a test suite for assessing the accuracy of new methods (or existing methods that are not included in this survey). Our test suite consists of five sets of nodes, with node counts ranging from 25 to 100, and 10 test functions. These are made available in the form of three Fortran subroutines: TESTDT returns one of the node sets; TSTFN1 returns a value and, optionally, a gradient value, of one of the test functions; and TSTFN2 returns a value, first partials, and second partial derivatives of one of the test functions.