lagrange_interp_1d, a MATLAB code which defines and evaluates the Lagrange polynomial p(x) which interpolates a set of data, so that p(x(i)) = y(i).
LAGRANGE_INTERP_1D needs the R8LIB library. The test uses the TEST_INTERP_1D library.
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
lagrange_interp_1d is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version and a Python version.
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).
divdif, a MATLAB code which uses divided differences to compute the polynomial interpolant to a given set of data.
fem1d_lagrange, a MATLAB code which sets up the matrices and vectors associated with the finite element method (fem) solution of a boundary value problem (bvp) -u''+u=f(x), using lagrange basis polynomials.
hermite_interpolant, a MATLAB code which computes the hermite interpolant, a polynomial that matches function values and derivatives.
lagrange_approx_1d, a MATLAB code which defines and evaluates the lagrange polynomial p(x) of degree m which approximates a set of nd data points (x(i),y(i)).
lagrange_basis_display, a MATLAB code which displays the basis functions associated with a given set of nodes used with the lagrange interpolation scheme.
lagrange_interp_2d, a MATLAB 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).
lagrange_interp_nd, a MATLAB code which defines and evaluates the lagrange polynomial p(x) which interpolates a set of data depending on a multidimensional argument x that was evaluated on a product grid, so that p(x(i)) = z(i).
nearest_interp_1d, a MATLAB code which interpolates a set of data using a piecewise constant interpolant defined by the nearest neighbor criterion.
newton_interp_1d, a MATLAB code which finds a polynomial interpolant to data using newton divided differences.
pwl_interp_1d, a MATLAB code which interpolates a set of data using a piecewise linear interpolant.
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, which are based on inverse distance weighting.
spline, a MATLAB code which constructs and evaluates spline interpolants and approximants.
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.