/* nag_fit_dim1_cheb_integ (e02ajc) Example Program.
 *
 * Copyright 2023 Numerical Algorithms Group.
 *
 * Mark 29.3, 2023.
 */

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

int main(void) {
  /* Initialized data */
  const double xmin = -0.5;
  const double xmax = 2.5;
  const double a[7] = {2.53213, 1.13032, 0.2715, 0.04434,
                       0.00547, 5.4e-4,  4e-5};

  /* Scalars */
  double ra, rb, result, xa, xb, zero;
  Integer exit_status, n, one;
  NagError fail;

  /* Arrays */
  double *aint = 0;

  INIT_FAIL(fail);

  exit_status = 0;
  printf("nag_fit_dim1_cheb_integ (e02ajc) Example Program Results\n");

  n = 6;
  zero = 0.0;
  one = 1;

  /* Allocate memory */
  if (!(aint = NAG_ALLOC(n + 2, double))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

  /* nag_fit_dim1_cheb_integ (e02ajc).
   * Integral of fitted polynomial in Chebyshev series form
   */
  nag_fit_dim1_cheb_integ(n, xmin, xmax, a, one, zero, aint, one, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_fit_dim1_cheb_integ (e02ajc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  xa = 0.0;
  xb = 2.0;
  /* nag_fit_dim1_cheb_eval2 (e02akc).
   * Evaluation of fitted polynomial in one variable from
   * Chebyshev series form
   */
  nag_fit_dim1_cheb_eval2(n + 1, xmin, xmax, aint, one, xa, &ra, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_fit_dim1_cheb_eval2 (e02akc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* nag_fit_dim1_cheb_eval2 (e02akc), see above. */
  nag_fit_dim1_cheb_eval2(n + 1, xmin, xmax, aint, one, xb, &rb, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_fit_dim1_cheb_eval2 (e02akc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  result = rb - ra;
  printf("\n");
  printf("Value of definite integral is %10.4f\n", result);
END:
  NAG_FREE(aint);

  return exit_status;
}