/* D01RL_P0W_F C++ Header Example Program.
 *
 * Copyright 2019 Numerical Algorithms Group.
 * Mark 27, 2019.
 */

#include <nag.h>
#include <nagad.h>
#include <stdio.h>
#include <math.h>
#include <iostream>
using namespace std;

extern "C"
{
  static void NAG_CALL f(void * &ad_handle,
                         const double x[],
                         const Integer &nx,
                         double fv[],
                         Integer &iflag,
                         Integer iuser[],
                         double ruser[],
                         const void *&cpuser);
}

int main(void)
{
  // Scalars
  int               exit_status = 0;

  cout << "D01RL_P0W_F C++ Header Example Program Results\n\n";

  double a, b, epsabs, epsrel;
  a = 0.0;
  b = 1.0;
  epsabs = 0.0;
  epsrel = 1.0e-4;
  
  Integer npts   = 1;
  Integer maxsub = 20;
  Integer lrinfo = 80 + npts + 6;
  Integer liinfo = 40 + npts + 4;
  double  *rinfo = 0;
  Integer *iinfo = 0;
  
  rinfo = new double [lrinfo];
  iinfo = new Integer [liinfo];

  void    *ad_handle = 0;
  double  result, abserr, ruser[20], points[1];
  Integer iuser[1];
  const void *cpuser = 0;
  points[0] = 1.0/7.0;
  iuser[0] = 0;
  for (int i = 0; i<20; ++i) {
    ruser[i] = 0.0;
  }
  
  // Call the passive routine

  Integer ifail = -1;
  d01rl_p0w_f_(ad_handle,f,a,b,npts,points,epsabs,epsrel,maxsub,result,abserr,
               rinfo,iinfo,iuser,ruser,cpuser,ifail);
  if (ifail<0) {
    cout << "\n ** d01rl_p0w_f_ failed error exit ifail = " << ifail << endl;
    goto END;
  }
  // Print inputs and primal outputs.
  cout << "\n lower limit of integration (a) = " << a << endl;
  cout << " upper limit of integration (b) = " << b << endl;
  cout << " given break point (points[0])  = " << points[0] << endl;
  cout << " absolute accuracy requested    = " << epsabs << endl;
  cout << " relative accuracy requested    = " << epsrel << endl;
  cout << " maximum number of subintervals = " << maxsub << endl;
  cout.setf(ios::scientific,ios::floatfield);
  cout.precision(4);
  if (ifail >= 0) {
    cout << "\n approximation to the integral  : " << result << endl;
    cout << " estimate of the absolute error : " << abserr << endl;
    cout << " number of function evaluations : " << iinfo[0] << endl;
  }

END:

  delete [] rinfo;
  delete [] iinfo;
  return exit_status;
}

static void NAG_CALL f(void * &ad_handle,
                       const double x[],
                       const Integer &nx,
                       double fv[],
                       Integer &iflag,
                       Integer iuser[],
                       double ruser[],
                       const void *&cpuser)
{
  iflag = 0;
  for (int i=0; i<nx; i++) {
    fv[i] = x[i] - 1.0/7.0;
    if (fv[i] == 0.0) {
      ruser[iflag] = x[i];
      iflag++;
    } else if (fv[i] < 0.0) {
      fv[i] = -fv[i];
    }
  }
  iuser[0] = iflag;
  if (iflag == 0) {
    for (int i=0; i<nx; i++) {
      fv[i] = 1.0/sqrt(fv[i]);
    }
  } else {
    iflag = -iflag;
  } 
  return;
}