INTERP
Interpolation Routines

INTERP is a MATLAB program 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 FORTRAN90 version and a MATLAB version.

Related Data and Programs:

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

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

LAGRANGE_INTERP_1D, a MATLAB library which defines and evaluates the Lagrange polynomial p(x) which interpolates a set of data, so that p(x(i)) = y(i).

RBF_INTERP_1D, a MATLAB library which defines and evaluates radial basis function (RBF) interpolants to 1D data.

SHEPARD_INTERP_1D, a MATLAB library which defines and evaluates Shepard interpolants to 1D data, which are based on inverse distance weighting.

SPARSE_INTERPOLANT a MATLAB library which can be used to define a sparse interpolant to a function f(x) of a multidimensional argument.

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

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

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

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

VANDERMONDE_INTERP_1D, a MATLAB library which finds a polynomial interpolant to data by setting up and solving a linear system involving the Vandermonde matrix.

Reference:

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

Source Code:

• cc_abscissas.m, computes the Clenshaw Curtis abscissas.
• cc_abscissas_ab.m, computes the Clenshaw Curtis abscissas for the interval [A,B].
• f1_abscissas.m, computes Fejer type 1 abscissas.
• f1_abscissas_ab.m, computes Fejer type 1 abscissas for the interval [A,B].
• f2_abscissas.m, computes Fejer Type 2 abscissas.
• f2_abscissas_ab.m, computes Fejer Type 2 abscissas for the interval [A,B].
• interp_lagrange.m, Lagrange polynomial interpolation to a curve in M dimensions.
• interp_linear.m, piecewise linear interpolation to a curve in M dimensions.
• interp_nearest.m, Nearest neighbor interpolation to a curve in M dimensions.
• lagrange_value.m, evaluates the Lagrange polynomials.
• ncc_abscissas.m, computes the Newton Cotes Closed abscissas.
• ncc_abscissas_ab.m, computes the Newton Cotes Closed abscissas for [A,B].
• nco_abscissas.m, computes the Newton Cotes Open abscissas.
• nco_abscissas_ab.m, computes the Newton Cotes Open abscissas for [A,B].
• parameterize_arc_length.m, parameterizes data by pseudo-arclength.
• parameterize_index.m, parameterizes data by its index.
• r8mat_expand_linear2.m, expands an R8MAT by linear interpolation.
• r8vec_ascends_strictly.m, determines if an R8VEC is strictly ascending.
• r8vec_bracket.m, searches a sorted R8VEC for successive brackets of a value.
• r8vec_expand_linear.m, linearly interpolates new data into an R8VEC.
• r8vec_expand_linear2.m, linearly interpolates new data into an R8VEC.
• r8vec_sorted_nearest.m, returns the nearest element in a sorted R8VEC.
• timestamp.m, prints the current YMDHMS date as a time stamp.

Examples and Tests:

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

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