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PWL_INTERP_2D_SCATTERED\ Piecewise Linear Interpolant to 2D Scattered Data {#pwl_interp_2d_scattered-piecewise-linear-interpolant-to-2d-scattered-data align=”center”} =================================================

PWL_INTERP_2D_SCATTERED is a C++ library which produces a piecewise linear interpolant to 2D scattered data, that is, data that is not guaranteed to lie on a regular grid.

This program computes a Delaunay triangulation of the data points, and then constructs an interpolant triangle by triangle. Over a given triangle, the interpolant is the linear function which matches the data already given at the vertices of the triangle.

PWL_INTERP_2D requires the R8LIB library. The test code requires the TEST_INTERP_2D library.

Licensing: {#licensing align=”center”}

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

Languages: {#languages align=”center”}

PWL_INTERP_2D_SCATTERED is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version.

LAGRANGE_INTERP_2D, a C++ library 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).

PWL_INTERP_2D, a C++ library which evaluates a piecewise linear interpolant to data defined on a regular 2D grid.

RBF_INTERP_2D, a C++ library which defines and evaluates radial basis function (RBF) interpolants to scattered 2D data.

SHEPARD_INTERP_2D, a C++ library which defines and evaluates Shepard interpolants to scattered 2D data, based on inverse distance weighting.

TEST_INTERP_2D, a C++ library which defines test problems for interpolation of regular or scattered data z(x,y), depending on a 2D argument.

TRIANGULATION, a C++ library which performs various operations on order 3 (linear) or order 6 (quadratic) triangulations.

TRIANGULATION_ORDER3_CONTOUR, a MATLAB program which makes contour plot of scattered data, or of data defined on an order 3 triangulation.

VANDERMONDE_INTERP_2D, a C++ library which finds a polynomial interpolant to data z(x,y) of a 2D argument by setting up and solving a linear system for the polynomial coefficients, involving the Vandermonde matrix.

Reference: {#reference align=”center”}

William Press, Brian Flannery, Saul Teukolsky, William Vetterling,\ Numerical Recipes in FORTRAN: The Art of Scientific Computing,\ Third Edition,\ Cambridge University Press, 2007,\ ISBN13: 978-0-521-88068-8,\ LC: QA297.N866.

Source Code: {#source-code align=”center”}

pwl_interp_2d_scattered.cpp, the source code.
pwl_interp_2d_scattered.hpp, the include file.

Examples and Tests: {#examples-and-tests align=”center”}

pwl_interp_2d_scattered_prb.cpp, a sample calling program.
pwl_interp_2d_scattered_prb_output.txt, the output file.

List of Routines: {#list-of-routines align=”center”}

DIAEDG chooses a diagonal edge.
I4_SIGN evaluates the sign of an I4.
I4MAT_TRANSPOSE_PRINT prints an I4MAT, transposed.
I4MAT_TRANSPOSE_PRINT_SOME prints some of the transpose of an I4MAT.
I4VEC_HEAP_D reorders an I4VEC into a descending heap.
I4VEC_MIN computes the minimum element of an I4VEC.
I4VEC_SORT_HEAP_A ascending sorts an I4VEC using heap sort.
I4VEC_SORTED_UNIQUE gets the unique elements in a sorted I4VEC.
LRLINE determines if a point is left of, right or, or on a directed line.
PERM_CHECK2 checks that a vector represents a permutation.
PERM_INVERSE inverts a permutation “in place”.
PWL_INTERP_2D_SCATTERED_VALUE evaluates a 2d interpolant of scattered data
R8TRIS2 constructs a Delaunay triangulation of 2D vertices.
SWAPEC swaps diagonal edges until all triangles are Delaunay.
TRIANGULATION_ORDER3_PRINT prints information about a triangulation.
TRIANGULATION_SEARCH_DELAUNAY searches a Delaunay triangulation for a point.
VBEDG determines which boundary edges are visible to a point.

You can go up one level to the C++ source codes.

Last revised on 24 October 2012.