interp, a FORTRAN90 code which takes a set of data associated with successive values of a parameter, and produces an interpolating function which can be evaluated over a continuous range of the parameter.


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


interp is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version.

Related Data and Programs:

BERNSTEIN_POLYNOMIAL, a FORTRAN90 code which evaluates the Bernstein polynomials, useful for uniform approximation of functions;

DIVDIF, a FORTRAN90 code which uses divided differences to interpolate data.

hermite_polynomial, a FORTRAN90 code which computes the Hermite interpolant, a polynomial that matches function values and derivatives.


NMS, a FORTRAN90 code which includes a package for the computation of piecewise cubic Hermite splines.

PPPACK, a FORTRAN90 code which implements Carl de Boor's piecewise polynomial functions, including, in particular, cubic splines.

RBF_INTERP, a FORTRAN90 code which defines and evaluates radial basis interpolants to multidimensional data.

SPLINE, a FORTRAN90 code which computes functions that approximate or interpolate data.

TEST_APPROX, a FORTRAN90 code which defines a number of test problems for approximation and interpolation.

TEST_INTERP_1D, a FORTRAN90 code which defines test problems for interpolation of data y(x), depending on a 1D argument.


  1. Samuel Conte, Carl deBoor,
    Elementary Numerical Analysis,
    Second Edition,
    McGraw Hill, 1972,
    ISBN: 07-012446-4,
    LC: QA297.C65.

Source Code:

Last revised on 18 July 2020.