/* nag_1d_quad_vals (d01gac) 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 <nagd01.h>

int main(int argc, char *argv[])
{
  FILE     *fpin, *fpout;

  Integer  exit_status = 0, i, n;
  NagError fail;
  double   ans, error, *x = 0, *y = 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_1d_quad_vals (d01gac) Example Program Results\n");
  fscanf(fpin, "%*[^\n]");    /* Skip heading in data file */
  fscanf(fpin, "%ld", &n);
  if (n >= 4)
    {
      if (!(x = NAG_ALLOC(n, double)) ||
          !(y = 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 (i = 0; i < n; ++i)
    fscanf(fpin, "%lf%lf", &x[i], &y[i]);
  /* nag_1d_quad_vals (d01gac).
   * One-dimensional integration of a function defined by data
   * values only
   */
  nag_1d_quad_vals(n, x, y, &ans, &error, &fail);
  if (fail.code == NE_NOERROR)
    {
      fprintf(fpout, "Integral = %7.4f\n", ans);
      fprintf(fpout, "Estimated error = %7.4f\n", error);
    }
  else
    {
      fprintf(fpout, "Error from nag_1d_quad_vals (d01gac).\n%s\n",
              fail.message);
      fprintf(fpout, "%s\n", fail.message);
      exit_status = 1;
    }
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (x) NAG_FREE(x);
  if (y) NAG_FREE(y);
  return exit_status;
}