test_interp_2d, a C code which defines test problems for interpolation of data z(x,y)), depending on a 2D argument.

The code requires access to the R8LIB library.


The computer code and data files described and made available on this web page are distributed under the MIT license


test_interp_2d is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version and a Python version.

Related Data and Programs:

LAGRANGE_INTERP_2D, a C code which defines and evaluates the Lagrange polynomial p(x,y) which interpolates a set of data depending on a 2D argument that was evaluated on a product grid, so that p(x(i),y(j)) = z(i,j).

PADUA, a C code which returns the points and weights for Padu sets, useful for interpolation in 2D. GNUPLOT is used to plot the points.

PWL_INTERP_2D, a C code which evaluates a piecewise linear interpolant to data defined on a regular 2D grid.

R8LIB, a C code which contains many utility routines, using double precision real (R8) arithmetic.

RBF_INTERP_2D, a C code which defines and evaluates radial basis function (RBF) interpolants to data in two dimensions.

TEST_INTERP_1D, a C code which defines test problems for interpolation of data y(x), depending on a 1D argument.


TEST_INTERP_ND, a C code which defines test problems for interpolation of data z(x), depending on an M-dimensional argument.

TOMS886, a C code which defines the Padua points for interpolation in a 2D region, including the rectangle, triangle, and ellipse, by Marco Caliari, Stefano de Marchi, Marco Vianello. This is a C version of ACM TOMS algorithm 886.


  1. Richard Franke,
    A Critical Comparison of Some Methods for Interpolation of Scattered Data,
    Naval Postgraduate School Technical Report,
    NPS-53-79-003, 1979.
  2. Robert Renka, Ron Brown,
    Algorithm 792: Accuracy Tests of ACM Algorithms for Interpolation of Scattered Data in the Plane,
    ACM Transactions on Mathematical Software,
    Volume 25, Number 1, March 1999, pages 78-94.
  3. Donald Shepard,
    A two-dimensional interpolation function for irregularly spaced data,
    ACM '68: Proceedings of the 1968 23rd ACM National Conference,
    ACM, pages 517-524, 1969.

Source Code:

Last revised on 14 August 2019.