/* D01FC_T1W_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 Integer& ndim,
                         const nagad_t1w_w_rtype z[],
                         nagad_t1w_w_rtype& fz,
                         Integer iuser[],
                         nagad_t1w_w_rtype ruser[]);
}

int main(void)
{
  // Scalars
  int               exit_status = 0;
  Integer           ndim = 4, maxpts = 4000, lenwrk = 100;

  cout << "D01FC_T1W_F C++ Header Example Program Results\n\n";

  // Allocate memory
  nagad_t1w_w_rtype *a = 0, *b = 0, *work = 0;

  a = new nagad_t1w_w_rtype [ndim];
  b = new nagad_t1w_w_rtype [ndim];
  work = new nagad_t1w_w_rtype [lenwrk];

  // Create AD configuration data object
  Integer ifail = 0;
  void    *ad_handle = 0;
  x10aa_t1w_f_(ad_handle,ifail);

  // Initialize variables
  for (int i = 0; i < ndim; i++) {
    a[i] = 0.0;
    b[i] = 1.0;
  }
  Integer           minpts = 0;
  nagad_t1w_w_rtype eps = 0.0001;
  nagad_t1w_w_rtype ruser[3];
  ruser[0] = 4.0;
  ruser[1] = 2.0;
  ruser[2] = 1.0;

  // Call the AD routine once for each active input
  ifail = 0;
  nagad_t1w_w_rtype finval, acc;
  Integer           iuser[1];
    
  double inc = 1.0, zero = 0.0;
  double dr[3];

  for ( int i = 0; i < 3; ++i) {
    nagad_t1w_inc_derivative(&ruser[i],inc);
    d01fc_t1w_f_(ad_handle,ndim,a,b,minpts,maxpts,f,eps,acc,lenwrk,
                 work,finval,iuser,ruser,ifail);
    nagad_t1w_set_derivative(&ruser[i],zero);
    dr[i] = nagad_t1w_get_derivative(finval);
  }

  cout << "\n Derivatives calculated: First order tangents\n";
  cout << " Computational mode    : algorithmic\n";

  cout.setf(ios::scientific,ios::floatfield);
  cout.setf(ios::right);
  cout.precision(4);
  cout << "\n Solution, x = ";
  double ans_value = nagad_t1w_get_value(finval);
  cout.width(12); cout << ans_value << endl;
  cout << "\n Derivatives:\n";
  cout <<  " d/druser[0] = ";
  cout.width(12); cout << dr[0] << endl;
  cout <<  " d/druser[1] = ";
  cout.width(12); cout << dr[1] << endl;
  cout <<  " d/druser[2] = ";
  cout.width(12); cout << dr[2] << endl;

  // Remove computational data object
  x10ab_t1w_f_(ad_handle,ifail);

  delete [] a;
  delete [] b;
  delete [] work;
  return exit_status;
}

static void NAG_CALL f(void* &ad_handle,
                       const Integer& ndim,
                       const nagad_t1w_w_rtype z[],
                       nagad_t1w_w_rtype& fz,
                       Integer iuser[],
                       nagad_t1w_w_rtype ruser[])
{
  // dco/c++ overloading used here to perform AD
  nagad_t1w_w_rtype f1, f2, f3;

  f1 = ruser[0]*z[0]*z[2]*z[2];
  f2 = ruser[1]*z[0]*z[2];
  f2 = exp(f2);
  f3 = ruser[2] + z[1] + z[3];
  f3 = f3*f3;
  fz = f1*f2/f3;

  return;
}