BIVAR - Bivariate interpolation of scattered data

BIVAR accepts a set of (X,Y) data points scattered in 2D, with associated Z data values, and is able to construct a smooth interpolation function Z(X,Y), which agrees with the given data, and can be evaluated at other points in the plane.

Reference 1:

Hiroshi Akima,
A Method of Bivariate Interpolation and Smooth Surface Fitting for Values Given at Irregularly Distributed Points,
ACM Transactions on Mathematical Software,
Volume 4, Number 2, June 1978.

Reference 2:

Hiroshi Akima,
On Estimating Partial Derivatives for Bivariate Interpolation of Scattered Data,
Rocky Mountain Journal of Mathematics,
Volume 14, Number 1, Winter 1984.

Files you may copy include:

• bivar.f90, the source code.
• bivar_prb.f90, a sample problem.
• bivar_prb.out, sample problem output.

The list of routines includes:

• IDBVIP performs bivariate interpolation of irregular X, Y data.
• IDGRID organizes grid points for surface fitting.
• IDLCTN finds the triangle that contains a point.
• IDPDRV estimates first and second partial derivatives at data points.
• IDPTIP performs interpolation, determining a value of Z given X and Y.
• IDSFFT performs smooth surface fitting when the projections of the
• IDTANG performs triangulation.
• IDXCHG determines whether two triangles should be exchanged.

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