INTERP
Interpolation Routines

INTERP is a FORTRAN90 library 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.

Licensing:

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

Languages:

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 library which evaluates the Bernstein polynomials, useful for uniform approximation of functions;

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

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

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

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

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

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

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

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

Reference:

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

Source Code:

• interp.f90, the source code.

Examples and Tests:

• interp_test.f90, a sample calling program.
• interp_test.txt, the output file.

List of Routines:

• CC_ABSCISSAS computes the Clenshaw Curtis abscissas.
• CC_ABSCISSAS_AB computes the Clenshaw Curtis abscissas for the interval [A,B].
• F1_ABSCISSAS computes Fejer type 1 abscissas.
• F1_ABSCISSAS_AB computes Fejer type 1 abscissas for the interval [A,B].
• F2_ABSCISSAS computes Fejer Type 2 abscissas.
• F2_ABSCISSAS_AB computes Fejer Type 2 abscissas for the interval [A,B].
• INTERP_LAGRANGE: Lagrange polynomial interpolation to a curve in M dimensions.
• INTERP_LINEAR: piecewise linear interpolation to a curve in M dimensions.
• INTERP_NEAREST: Nearest neighbor interpolation to a curve in M dimensions.
• LAGRANGE_VALUE evaluates the Lagrange polynomials.
• NCC_ABSCISSAS computes the Newton Cotes Closed abscissas.
• NCC_ABSCISSAS_AB computes the Newton Cotes Closed abscissas for [A,B].
• NCO_ABSCISSAS computes the Newton Cotes Open abscissas.
• NCO_ABSCISSAS_AB computes the Newton Cotes Open abscissas for [A,B].
• PARAMETERIZE_ARC_LENGTH parameterizes data by pseudo-arclength.
• PARAMETERIZE_INDEX parameterizes data by its index.
• R8MAT_EXPAND_LINEAR2 expands an R8MAT by linear interpolation.
• R8VEC_ASCENDS_STRICTLY determines if an R8VEC is strictly ascending.
• R8VEC_BRACKET searches a sorted R8VEC for successive brackets of a value.
• R8VEC_EXPAND_LINEAR linearly interpolates new data into an R8VEC.
• R8VEC_EXPAND_LINEAR2 linearly interpolates new data into an R8VEC.
• R8VEC_SORTED_NEAREST returns the nearest element in a sorted R8VEC.
• TIMESTAMP prints the current YMDHMS date as a time stamp.

You can go up one level to the FORTRAN90 source codes.