# ncl_c_natgridd - Man Page

primary double precision C entry for natural neighbor gridding

## Function Prototype

double  *c_natgridd(int, double [], double [], double [],
int, int, double [], double [], int *);

## Synopsis

`double *c_natgridd (npnts, x, y, z, numxout, numyout, xi, yi, ier);`

## Description

npnts

The number of input data points. (npnts > 3).

x

An array containing the x coordinates of the input data points.

y

An array containing the y coordinates of the input data points.

z

An array containing the functional values of the  input data points. That is, z[m] is the value of the input function at  coordinate (x[m],y[m]), for 0 <= m < npnts.

numxout

The number of x values in the output grid.

numyout

The number of y values in the output grid.

xi

An array of dimension numxout containing the x  coordinates of the output data grid. The values in xi must be  increasing, but need not be equally spaced.

yi

An array of dimension numyout containing the y  coordinates of the output data grid. The values in yi must be  increasing, but need not be equally spaced.

ier

An error value. If *ier is 0, then no errors were detected. If *ier is non-zero, then refer to the man page for natgrid_errors for details.

## Usage

c_natgridd returns a pointer to a linear array of data that is is the interpolated grid stored in row-major order. That is, if out is declared as

double *out;

and we set:

out = c_natgridd(numin, x, y, z, numxout, numyout, xo, yo, &ier);

then out[i*numyout+j] is the interpolated function value at coordinate point (xo[i],yo[j]) for 0 <= i < numxout and 0 <= j < numyout. The space for out is allocated internal to c_natgrids and is numxout*numyout double values in size.

## Access

To use c_natgridd, load the NCAR Graphics library ngmath.

## See Also

natgrid, natgrid_params,  c_nnseti,  c_nngeti,  c_nnsetrd,  c_nngetrd,  c_nnsetc,  c_nngetc.

Complete documentation for Natgrid is available at URL
http://ngwww.ucar.edu/ngdoc/ng/ngmath/natgrid/nnhome.html

## Info

March 1997-1998 UNIX NCAR GRAPHICS