# ncl_shgrid - Man Page

interpolate random data in 3-space using a modified Shepard's algorithm

## Synopsis

CALL SHGRID (N, X, Y, Z, F, NXO, NYO, NZO, XO, YO, ZO,
FF, IWK, RWK, IER)

## Description

N

(integer,input) The number of input data points (N > 9).

X

(real, input) An array containing the X coordinates of the  input data points.  X is dimensioned for N.

Y

(real, input) An array containing the Y coordinates of the  input data points.  Y is dimensioned for N.

Z

(real, input) An array containing the Z coordinates of the  input data points.  Z is dimensioned for N.

F

(real, input) Array dimensioned for N containing data values.  F(I) is a functional value at (X(I),Y(I),Z(I)) for I = 1 to N.

NXO

(integer, input) The number of X coordinate values in the output grid.

NYO

(integer, input) The number of Y coordinate values in the output grid.

NZO

(integer, input) The number of Z coordinate values in the output grid.

XO

(real, input) An array dimensioned for NXO  containing the X coordinates of the output surface.

YO

(real, input) An array dimensioned for NYO containing the Y coordinates of the output surface.

ZO

(real, input) An array dimensioned for NZO containing the Y coordinates of the output surface.

FF

(real, output) An array dimensioned for NXO x NYO x NZO  containing the calculated function values for the output function.  FF(I,J,K) is the calculated functional value at (XO(I), YO(J), ZO(K)) for I=1,NXO and J=1,NYO and K=1,NZO.

IRK

(integer, input) An integer workspace of length at least 2*N.

RWK

(real, input) A work array dimensioned for 11*N+6.

IER

(integer, output) An error return value.  If IER is returned as 0, then no errors were detected. If IER is non-zero, then refer to the man page for shgrid_errors for details.

## Usage

SHGRID is called to interpolate randomly spaced data in 3-space.  SHGRID uses a modified Shepard's algorithm to construct an interpolatory  surface.

## Access

To use SHGRID, load the NCAR Graphics library ngmath.