/* nag_monotonic_intg (e01bhc) Example Program.
 *
 * Copyright 1991 Numerical Algorithms Group.
 *
 * Mark 2, 1991.
 * Mark 8 revised, 2004.
 */

#include <nag.h>
#include <nagx04.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <nage01.h>

int main(int argc, char *argv[])
{
  FILE     *fpin, *fpout;
  Integer  exit_status = 0, n, r;
  NagError fail;
  double   a, b, *d = 0, *f = 0, integral, *x = 0;

  INIT_FAIL(fail);

  /* Check for command-line IO options */
  fpin = nag_example_file_io(argc, argv, "-data", NULL);
  fpout = nag_example_file_io(argc, argv, "-results", NULL);
  fprintf(fpout, "nag_monotonic_intg (e01bhc) Example Program Results\n");
  fscanf(fpin, "%*[^\n]");  /* Skip heading in data file */
  fscanf(fpin, "%ld", &n);
  if (n >= 2)
    {
      if (!(d = NAG_ALLOC(n, double)) ||
          !(f = NAG_ALLOC(n, double)) ||
          !(x = NAG_ALLOC(n, double)))
        {
          fprintf(fpout, "Allocation failure\n");
          exit_status = -1;
          goto END;
        }
    }
  else
    {
      fprintf(fpout, "Invalid n.\n");
      exit_status = 1;
      return exit_status;
    }
  for (r = 0; r < n; r++)
    fscanf(fpin, "%lf%lf%lf", &x[r], &f[r], &d[r]);
  fprintf(fpout, "                                          Integral\n");
  fprintf(fpout, "          a                  b            over (a,b)\n");
  /* Read a, b pairs until end of file and compute
   * definite integrals.
   */
  while (fscanf(fpin, "%lf%lf", &a, &b) != EOF)
    {
      /* nag_monotonic_intg (e01bhc).
       * Evaluation of interpolant computed by
       * nag_monotonic_interpolant (e01bec), definite integral
       */
      nag_monotonic_intg(n, x, f, d, a, b, &integral, &fail);
      if (fail.code != NE_NOERROR)
        {
          fprintf(fpout, "Error from nag_monotonic_intg (e01bhc).\n%s\n",
                  fail.message);
          exit_status = 1;
          goto END;
        }
      fprintf(fpout, "%13.4f      %13.4f      %13.4f\n", a, b, integral);
    }
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (d) NAG_FREE(d);
  if (f) NAG_FREE(f);
  if (x) NAG_FREE(x);
  return exit_status;
}