NAG Library Manual, Mark 27.3
Interfaces:  FL   CL   CPP   AD 

NAG CL Interface Introduction
Example description
/* nag_interp_dim3_scat_shep (e01tgc) Example Program.
 *
 * Copyright 2021 Numerical Algorithms Group.
 *
 * Mark 27.3, 2021.
 */

#include <nag.h>
#include <stdio.h>

int main(void) {
  /* Scalars */
  Integer exit_status, i, m, n, nq, nw, liq, lrq;
  NagError fail;

  /* Arrays */
  double *f = 0, *q = 0, *qx = 0, *qy = 0, *qz = 0, *rq = 0, *u = 0, *v = 0,
         *w = 0, *x = 0, *y = 0, *z = 0;
  Integer *iq = 0;

  exit_status = 0;

  INIT_FAIL(fail);

  printf("nag_interp_dim3_scat_shep (e01tgc) Example Program Results\n");

  /* Skip heading in data file */
  scanf("%*[^\n] ");

  /* Input the number of nodes. */
  scanf("%" NAG_IFMT "%*[^\n] ", &m);

  if (m > 0) {
    /* Allocate memory */
    lrq = 10 * m + 7;
    liq = 2 * m + 1;
    if (!(f = NAG_ALLOC(m, double)) || !(x = NAG_ALLOC(m, double)) ||
        !(y = NAG_ALLOC(m, double)) || !(z = NAG_ALLOC(m, double)) ||
        !(rq = NAG_ALLOC(lrq, double)) || !(iq = NAG_ALLOC(liq, Integer))) {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }

    /* Input the data points X,Y,Z and F. */
    for (i = 0; i < m; ++i)
      scanf("%lf%lf%lf%lf%*[^\n] ", &x[i], &y[i], &z[i], &f[i]);

    /* Generate the interpolant. */
    nq = 0;
    nw = 0;

    /* nag_interp_dim3_scat_shep (e01tgc).
     * Interpolating functions, modified Shepard's method, three
     * variables
     */
    nag_interp_dim3_scat_shep(m, x, y, z, f, nw, nq, iq, rq, &fail);
    if (fail.code != NE_NOERROR) {
      printf("Error from nag_interp_dim3_scat_shep (e01tgc).\n%s\n",
             fail.message);
      exit_status = 1;
      goto END;
    }

    /* Input the number of evaluation points. */
    scanf("%" NAG_IFMT "%*[^\n] ", &n);

    /* Allocate memory for nag_interp_dim3_scat_shep_eval (e01thc) */
    if (!(q = NAG_ALLOC(n, double)) || !(qx = NAG_ALLOC(n, double)) ||
        !(qy = NAG_ALLOC(n, double)) || !(qz = NAG_ALLOC(n, double)) ||
        !(u = NAG_ALLOC(n, double)) || !(v = NAG_ALLOC(n, double)) ||
        !(w = NAG_ALLOC(n, double))) {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }

    /* Input the evaluation points. */
    for (i = 0; i < n; ++i)
      scanf("%lf%lf%lf%*[^\n] ", &u[i], &v[i], &w[i]);

    /* Evaluate the interpolant using nag_interp_dim3_scat_shep_eval (e01thc).
     */
    fail.print = Nag_TRUE;
    /* nag_interp_dim3_scat_shep_eval (e01thc).
     * Interpolated values, evaluate interpolant computed by
     * nag_interp_dim3_scat_shep (e01tgc), function and first
     * derivatives, three variables
     */
    nag_interp_dim3_scat_shep_eval(m, x, y, z, f, iq, rq, n, u, v, w, q, qx, qy,
                                   qz, &fail);

    printf("\n");
    printf("     i     u(i)      v(i)      w(i)      Q(i)\n");
    for (i = 0; i < n; ++i)
      printf("%6" NAG_IFMT "%10.4f%10.4f%10.4f%10.4f\n", i, u[i], v[i], w[i],
             q[i]);
  }

END:
  NAG_FREE(f);
  NAG_FREE(q);
  NAG_FREE(qx);
  NAG_FREE(qy);
  NAG_FREE(qz);
  NAG_FREE(rq);
  NAG_FREE(u);
  NAG_FREE(v);
  NAG_FREE(w);
  NAG_FREE(x);
  NAG_FREE(y);
  NAG_FREE(z);
  NAG_FREE(iq);

  return exit_status;
}