/* nag_1d_quad_brkpts_1 (d01slc) Example Program.
 *
 * Copyright 1998 Numerical Algorithms Group.
 *
 * Mark 5, 1998.
 * Mark 6 revised, 2000.
 * Mark 7 revised, 2001.
 *
 */

#include <nag.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <math.h>
#include <nagd01.h>

#ifdef __cplusplus
extern "C" {
#endif
  static double f(double x, Nag_User *comm);
#ifdef __cplusplus
}
#endif

int main(void)
{

  double a, b;
  double epsabs, abserr, epsrel, brkpts[1], result;
  Integer nbrkpts;
  Nag_QuadProgress qp;
  Integer max_num_subint;
  static NagError fail;
  Nag_User comm;

  Vprintf("nag_1d_quad_brkpts_1 (d01slc) Example Program Results\n");
  nbrkpts = 1;
  epsabs = 0.0;
  epsrel = 0.001;
  a = 0.0;
  b = 1.0;
  max_num_subint = 200;
  brkpts[0] = 1.0/7.0;
  /* nag_1d_quad_brkpts_1 (d01slc).
   * One-dimensional adaptive quadrature, allowing for
   * singularities at specified points, thread-safe
   */
  nag_1d_quad_brkpts_1(f, a, b, nbrkpts, brkpts, epsabs, epsrel, max_num_subint,
                       &result, &abserr, &qp, &comm, &fail);

  Vprintf("a      - lower limit of integration = %10.4f\n", a);
  Vprintf("b      - upper limit of integration = %10.4f\n", b);
  Vprintf("epsabs - absolute accuracy requested = %9.2e\n", epsabs);
  Vprintf("epsrel - relative accuracy requested = %9.2e\n\n", epsrel);
  Vprintf("brkpts[0] - given break-point = %10.4f\n", brkpts[0]);
  if (fail.code != NE_NOERROR)
    Vprintf("%s\n", fail.message);
  if (fail.code != NE_INT_ARG_LT && fail.code != NE_2_INT_ARG_LE &&
      fail.code != NE_ALLOC_FAIL && fail.code != NE_NO_LICENCE)
    {
      /* Free memory used by qp */
      NAG_FREE(qp.sub_int_beg_pts);
      NAG_FREE(qp.sub_int_end_pts);
      NAG_FREE(qp.sub_int_result);
      NAG_FREE(qp.sub_int_error);
    }
  if (fail.code != NE_INT_ARG_LT && fail.code != NE_2_INT_ARG_LE
      && fail.code != NE_QUAD_BRKPTS_INVAL && fail.code != NE_ALLOC_FAIL)
    {
      Vprintf("result - approximation to the integral = %9.5f\n", result);
      Vprintf("abserr - estimate of the absolute error = %9.2e\n", abserr);
      Vprintf("qp.fun_count  - number of function evaluations = %4ld\n",
              qp.fun_count);
      Vprintf("qp.num_subint  - number of subintervals used = %4ld\n",
              qp.num_subint);
      return EXIT_SUCCESS;
    }
  return EXIT_FAILURE;
}
static double f(double x, Nag_User *comm)
{
  double a;
  a = FABS(x-1.0/7.0);
  return (a != 0.0) ? pow(a, -0.5): 0.0;
}