QSHEP2D
Interpolation of Scattered Data in the Plane

QSHEP2D is a FORTRAN90 library which interpolates scattered 2D data.

QSHEP2D takes a set of data values ZDAT(XDAT,YDAT), where the points (XDAT,YDAT) are "scattered" in the plane, and constructs an interpolating function Z(X,Y) which matches the given data, and extends smoothly through the plane.

QSHEP2D is primarily a FORTRAN90 "translation" of a FORTRAN77 program which was written by Robert Renka and published in the ACM Transactions on Mathematical Software.

QSHEP2D is ACM Transactions on Mathematical Software Algorithm number 660. The original text of any ACM TOMS algorithm is available through ACM: http://www.acm.org/pubs/calgo or NETLIB: http://www.netlib.org/toms/index.html

Related Data and Programs:

BIVAR is a FORTRAN90 library which takes scattered 2D data and produces an interpolating function F(X,Y).

QSHEP3D is a FORTRAN90 library which takes scattered 3D data and produces an interpolating function F(X,Y,Z).

Author:

Robert Renka

Reference:

1. Robert Renka,
   Algorithm 660,
   QSHEP2D, Quadratic Shepard method for bivariate interpolation of scattered data,
   ACM Transactions on Mathematical Software,
   Volume 14, 1988, pages 149-150.

Source Code:

• qshep2d.f90, the source code.
• qshep2d.csh, commands to compile the source code.

Examples and Tests:

• qshep2d_prb.f90, a sample problem.
• qshep2d_prb.csh, commands to compile, load and run the sample problem.
• qshep2d_prb_output.txt, the output file.

List of Routines:

• GETNP2 seeks the closest unmarked node to a point.
• GIVENS constructs a Givens plane rotation.
• QS2GRD evaluates the interpolant and its first spatial derivatives.
• QSHEP2 computes an interpolant to scattered data in the plane.
• QS2VAL evaluates the interpolant function at a point.
• ROTATE applies a Givens rotation.
• SETUP2 sets up a row of the least squares regression matrix.
• STORE2 creates a cell data structure for the scattered data.

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