# shepard_interp_1d

shepard_interp_1d, a MATLAB code which defines and evaluates Shepard interpolants to 1D data, based on inverse distance weighting.

SHEPARD_interp_1d needs the R8LIB library. The test code also needs the TEST_INTERP library.

### Languages:

shepard_interp_1d 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:

barycentric_interp_1d, a MATLAB code which defines and evaluates the barycentric Lagrange polynomial p(x) which interpolates a set of data, so that p(x(i)) = y(i). The barycentric approach means that very high degree polynomials can safely be used.

chebyshev_interp_1d, a MATLAB code which determines the combination of Chebyshev polynomials which interpolates a set of data, so that p(x(i)) = y(i).

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r8lib, a MATLAB code which contains many utility routines using double precision real (R8) arithmetic.

rbf_interp_1d, a MATLAB code which defines and evaluates radial basis function (RBF) interpolants to 1D data.

shepard_interp_1d, a MATLAB code which defines and evaluates Shepard interpolants to 1D data, based on inverse distance weighting.

shepard_interp_2d, a MATLAB code which defines and evaluates Shepard interpolants to 2D data, based on inverse distance weighting.

shepard_interp_nd, a MATLAB code which defines and evaluates Shepard interpolants to multidimensional data, based on inverse distance weighting.

test_interp, a MATLAB code which defines a number of test problems for interpolation, provided as a set of (x,y) data.

test_interp_1d, a MATLAB code which defines test problems for interpolation of data y(x), depending on a 2D argument.

vandermonde_interp_1d, a MATLAB code which finds a polynomial interpolant to a function of 1D data by setting up and solving a linear system for the polynomial coefficients, involving the Vandermonde matrix.

### Reference:

1. Richard Franke,
Scattered Data Interpolation: Tests of Some Methods,
Mathematics of Computation,
Volume 38, Number 157, January 1982, pages 181-200.
2. 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.