NAG Library Manual, Mark 29.2
Interfaces:  FL   CL   CPP   AD 

NAG CL Interface Introduction
Example description
/* nag_smooth_kerndens_gauss (g10bbc) Example Program.
 *
 * Copyright 2023 Numerical Algorithms Group.
 *
 * Mark 29.2, 2023.
 */
/* Pre-processor includes */
#include <nag.h>
#include <stdio.h>

int main(void) {
  /* Integer scalar and array declarations */
  Integer n, ns, i;
  Integer exit_status = 0;

  /* Nag Types */
  NagError fail;
  Nag_Boolean fcall;
  Nag_WindowType wtype;

  /* Double scalar and array declarations */
  double shi, slo, window;
  double *rcomm = 0, *smooth = 0, *t = 0, *x = 0;

  /* Character scalar and array declarations */
  char cwtype[40];

  /* Initialize the error structure */
  INIT_FAIL(fail);

  printf("nag_smooth_kerndens_gauss (g10bbc) Example Program Results\n\n");

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

  /* Read in density estimation information */
  scanf("%39s %lf %lf %lf %" NAG_IFMT "%*[^\n] ", cwtype, &window, &slo, &shi,
        &ns);
  wtype = (Nag_WindowType)nag_enum_name_to_value(cwtype);

  /* Read in the size of the dataset */
  scanf("%" NAG_IFMT "%*[^\n] ", &n);

  if (!(smooth = NAG_ALLOC(ns, double)) || !(t = NAG_ALLOC(ns, double)) ||
      !(rcomm = NAG_ALLOC(ns + 20, double)) || !(x = NAG_ALLOC(n, double))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

  /* Only calling the routine once */
  fcall = Nag_TRUE;

  /* Read in data */
  for (i = 0; i < n; i++) {
    scanf("%lf", &x[i]);
  }
  scanf("%*[^\n] ");

  /* Call nag_smooth_kerndens_gauss (g10bbc) to perform kernel
   * density estimation
   */
  nag_smooth_kerndens_gauss(n, x, wtype, &window, &slo, &shi, ns, smooth, t,
                            fcall, rcomm, &fail);
  if (fail.code != NE_NOERROR && fail.code != NW_POTENTIAL_PROBLEM) {
    printf("Error from nag_smooth_kerndens_gauss (g10bbc).\n%s\n",
           fail.message);
    exit_status = -1;
    goto END;
  }

  /* Display the summary of results */
  printf("Window Width Used = %13.4e\n", window);
  printf("Interval = (%13.4e,%13.4e)\n", slo, shi);
  printf("\n");
  printf("First %" NAG_IFMT " output values:\n", MIN(ns, 20));
  printf("\n");
  printf("      Time        Density\n");
  printf("      Point       Estimate\n");
  printf(" ---------------------------\n");
  for (i = 0; i < MIN(20, ns); i++)
    printf(" %13.3e %13.3e\n", t[i], smooth[i]);

END:
  NAG_FREE(smooth);
  NAG_FREE(t);
  NAG_FREE(rcomm);
  NAG_FREE(x);

  return exit_status;
}