/* nag_1d_quad_inf_1 (d01smc) Example Program.
 *
 * Copyright 1998 Numerical Algorithms Group.
 *
 * Mark 5, 1998.
 * Mark 6 revised, 2000.
 * Mark 7 revised, 2001.
 *
 */

#include <nag.h>
#include <nagx04.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <math.h>
#include <nagd01.h>

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

int main(int argc, char *argv[])
{
  FILE             *fpout;
  Integer          exit_status = 0;
  double           a;
  double           epsabs, abserr, epsrel, result;
  Nag_QuadProgress qp;
  Integer          max_num_subint;
  NagError         fail;
  Nag_User         comm;

  INIT_FAIL(fail);

  /* Check for command-line IO options */
  fpout = nag_example_file_io(argc, argv, "-results", NULL);
  fprintf(fpout, "nag_1d_quad_inf_1 (d01smc) Example Program Results\n");
  epsabs = 0.0;
  epsrel = 0.0001;
  a = 0.0;
  max_num_subint = 200;

  /* nag_1d_quad_inf_1 (d01smc).
   * One-dimensional adaptive quadrature over infinite or
   * semi-infinite interval, thread-safe
   */
  nag_1d_quad_inf_1(f, Nag_UpperSemiInfinite, a, epsabs, epsrel,
                    max_num_subint, &result, &abserr, &qp, &comm, &fail);
  fprintf(fpout, "a      - lower limit of integration = %10.4f\n", a);
  fprintf(fpout, "b      - upper limit of integration = infinity\n");
  fprintf(fpout, "epsabs - absolute accuracy requested = %11.2e\n", epsabs);
  fprintf(fpout, "epsrel - relative accuracy requested = %11.2e\n\n", epsrel);
  if (fail.code != NE_NOERROR)
    fprintf(fpout, "Error from nag_1d_quad_inf_1 (d01smc)  %s\n", fail.message);
  if (fail.code != NE_INT_ARG_LT && fail.code != NE_BAD_PARAM &&
      fail.code != NE_ALLOC_FAIL && fail.code != NE_NO_LICENCE)
    {
      fprintf(fpout, "result - approximation to the integral = %9.5f\n",
              result);
      fprintf(fpout, "abserr - estimate of the absolute error = %11.2e\n",
              abserr);
      fprintf(fpout, "qp.fun_count  - number of function evaluations = %4ld\n",
              qp.fun_count);
      fprintf(fpout, "qp.num_subint  - number of subintervals used = %4ld\n",
              qp.num_subint);
      /* 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);
    }
  else
    {
      exit_status = 1;
      goto END;
    }

 END:
  if (fpout != stdout) fclose(fpout);
  return exit_status;
}

static double NAG_CALL f(double x, Nag_User *comm)
{
  return 1.0/((x+1.0)*sqrt(x));
}