NAG Library Manual, Mark 29.1
Interfaces:  FL   CL   CPP   AD 

NAG CL Interface Introduction
Example description
/* nag_sort_realvec_search (m01nac) Example Program.
 *
 * Copyright 2023 Numerical Algorithms Group.
 *
 * Mark 29.1, 2023.
 */
/* Pre-processor includes */
#include <math.h>
#include <nag.h>
#include <stdio.h>

int main(void) {
  /*Logical scalar and array declarations */
  Nag_Boolean validate;
  /*Integer scalar and array declarations */
  Integer exit_status = 0;
  Integer i, index, lenrv, m1, m2;
  /*Double scalar and array declarations */
  double item;
  double *rv = 0;
  NagError fail;

  INIT_FAIL(fail);

  printf("%s\n", "nag_sort_realvec_search (m01nac) Example Program Results");
  printf("\n");
  scanf("%*[^\n] ");
  scanf("%" NAG_IFMT "%*[^\n] ", &lenrv);
  if (!(rv = NAG_ALLOC(lenrv, double))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }
  /* Read in Reference Vector rv */
  for (i = 0; i < lenrv; i++)
    scanf("%lf ", &rv[i]);
  scanf("%*[^\n] ");
  /* Read items sought in the reference vector */
  validate = Nag_TRUE;
  while (scanf("%lf%*[^\n] ", &item) != EOF)
  {
    m1 = 0;
    m2 = lenrv - 1;
    /*
     * nag_sort_realvec_search (m01nac)
     * Binary search in set of double precision numbers
     */
    index = nag_sort_realvec_search(validate, rv, m1, m2, item, &fail);
    if (fail.code != NE_NOERROR) {
      printf("Error from nag_sort_realvec_search (m01nac).\n%s\n",
             fail.message);
      exit_status = 1;
      goto END;
    }
    if (validate) {
      /* Print the reference vector */
      printf("%s\n", "Reference Vector is:");
      for (i = 0; i < lenrv; i++)
        printf("%7.1f%s", rv[i], (i + 1) % 8 ? " " : "\n");
      printf("\n");
      validate = Nag_FALSE;
    }
    printf("\n");
    printf("  Search for item  %7.1f returned index: %4" NAG_IFMT "\n", item,
           index);
  }

END:
  NAG_FREE(rv);

  return exit_status;
}