/* D01RL_A1W_F C++ Header Example Program.
 *
 * Copyright 2019 Numerical Algorithms Group.
 * Mark 27, 2019.
 */

#include <nag.h>
#include <dco.hpp>
#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 nagad_a1w_w_rtype x[],
                         const Integer &nx,
                         nagad_a1w_w_rtype fv[],
                         Integer &iflag,
                         Integer iuser[],
                         nagad_a1w_w_rtype ruser[],
                         const void *&cpuser);
}

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

  cout << "D01RL_A1W_F C++ Header Example Program Results\n\n";

  // Create AD tape
  nagad_a1w_ir_create();

  nagad_a1w_w_rtype 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;
  nagad_a1w_w_rtype *rinfo = 0;
  Integer           *iinfo = 0;
  
  rinfo = new nagad_a1w_w_rtype [lrinfo];
  iinfo = new Integer [liinfo];

  // Create AD configuration data object
  Integer ifail = 0;
  void    *ad_handle = 0;
  x10aa_a1w_f_(ad_handle,ifail);

  double            inc = 1.0;
  nagad_a1w_w_rtype 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;
  }
  
  // Register variables to differentiate w.r.t.
  nagad_a1w_ir_register_variable(&a);
  nagad_a1w_ir_register_variable(&b);
  
  // Call the AD routine
  ifail = -1;
  d01rl_a1w_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_a1w_f_ failed error exit ifail = " << ifail << endl;
    goto END;
  }
  // Print inputs and primal outputs.
  cout << "\n lower limit of integration (a) = " << nagad_a1w_get_value(a) << endl;
  cout << " upper limit of integration (b) = " << nagad_a1w_get_value(b) << endl;
  cout << " given break point (points[0])  = " << nagad_a1w_get_value(points[0]) << endl;
  cout << " absolute accuracy requested    = " << nagad_a1w_get_value(epsabs) << endl;
  cout << " relative accuracy requested    = " << nagad_a1w_get_value(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  : " << nagad_a1w_get_value(result) << endl;
    cout << " estimate of the absolute error : " << nagad_a1w_get_value(abserr) << endl;
    cout << " number of function evaluations : " << iinfo[0] << endl;
  }

  // Setup evaluation of derivatives via adjoints.
  nagad_a1w_inc_derivative(&result,inc);
  ifail = 0;
  nagad_a1w_ir_interpret_adjoint(ifail);

  cout << "\n Derivatives calculated: First order adjoints\n";
  cout << " Computational mode    : algorithmic\n";
  
  // Get derivatives
  double dr;
  dr = nagad_a1w_get_derivative(a);
  cout << "\n Derivative of solution w.r.t end points:\n";
  cout << " dI/da = " << dr << endl;
  dr = nagad_a1w_get_derivative(b);
  cout << " dI/db = " << dr << endl;

END:
  // Remove computational data object and tape
  x10ab_a1w_f_(ad_handle,ifail);
  nagad_a1w_ir_remove();

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

static void NAG_CALL f(void * &ad_handle,
                       const nagad_a1w_w_rtype x[],
                       const Integer &nx,
                       nagad_a1w_w_rtype fv[],
                       Integer &iflag,
                       Integer iuser[],
                       nagad_a1w_w_rtype ruser[],
                       const void *&cpuser)
{
  // dco/c++ used here to perform AD of the following
  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;
}