SYNOPSIS

FUNCTION SURF2 (XX, YY, M, N, X, Y, Z, IZ, ZP, SIGMA)

This function interpolates a surface value at a specified coordinate using bi-splines under tension. SURF1 must be called before invoking SURF2. The desired interpolated value is returned as the value of the function.

DESCRIPTION

XX

(real, input) Contains the X coordinate of a point to be mapped onto the interpolated surface.

YY

(real, input) Contains the Y coordinate of a point to be mapped onto the interpolated surface.

M

(integer, input) The number of grid lines in the X direction. (M > 1)

N

(integer, input) The number of grid lines in the Y direction. (N > 1)

X

(real, input) An array containing M X coordinates for grid lines in the X direction. These values must be strictly increasing.

Y

(real, input) An array containing N Y coordinates for grid lines in the Y direction. These values must be strictly increasing.

Z

(real, input) An array containing M x N functional values at the grid points; Z(I,J) contains the functional value at (X(I),Y(J)) for I=1,M and J=1,N.

IZ

(integer, input) The row dimension of the matrix Z (IZ is greater than or equal to M).

ZP

(real, input) An array of size M x N x 3.

SIGMA

(real, input) Tension factor. Values near zero result in a cubic spline; large values (e.g. 50) result in nearly a polygonal line. A typical value is 1.

RETURN VALUE

SURF2 returns the interpolated value at the specified point T.

ACCESS

To use SURF2, load the NCAR Graphics library ngmath.

COPYRIGHT

Copyright (C) 2000
University Corporation for Atmospheric Research

The use of this Software is governed by a License Agreement.