/* D01FC_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 <nag_stdlib.h>
#include <iostream>
using namespace std;

extern "C"
{
  static void NAG_CALL f_a1w(void* &ad_handle,
                             const Integer& ndim,
                             const nagad_a1w_w_rtype z[],
                             nagad_a1w_w_rtype& fz,
                             Integer iuser[],
                             nagad_a1w_w_rtype ruser[]);
}

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

  cout << "D01FC_A1W_F C++ Header Example Program Results\n\n";

  // Allocate memory
  nagad_a1w_w_rtype *a = 0, *b = 0, *work = 0;

  if (!(a = NAG_ALLOC(ndim, nagad_a1w_w_rtype)) ||
      !(b = NAG_ALLOC(ndim, nagad_a1w_w_rtype)) ||
      !(work = NAG_ALLOC(lenwrk, nagad_a1w_w_rtype))) 
    {
      printf("Allocation failure\n");
      exit_status = -2;
    }
  
  if (exit_status==0) {

    // Create AD tape
    nagad_a1w_ir_create();

    // Create AD configuration data object
    Integer ifail = 0;
    void    *ad_handle = 0;
    x10aa_a1w_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_a1w_w_rtype eps = 0.0001;
    nagad_a1w_w_rtype ruser[3];
    ruser[0] = 4.0;
    ruser[1] = 2.0;
    ruser[2] = 1.0;


    /* Register variables to differentiate w.r.t. */
    nagad_a1w_ir_register_variable(&ruser[0]);
    nagad_a1w_ir_register_variable(&ruser[1]);
    nagad_a1w_ir_register_variable(&ruser[2]);
    
    // Call the AD routine
    ifail = 0;
    nagad_a1w_w_rtype finval, acc;
    Integer           iuser[1];
    d01fc_a1w_f_(ad_handle,ndim,a,b,minpts,maxpts,f_a1w,eps,acc,lenwrk,
                 work,finval,iuser,ruser,ifail);

    double inc = 1.0;
    nagad_a1w_inc_derivative(&finval,inc);
    nagad_a1w_ir_interpret_adjoint(ifail);

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

    // Get derivatives
    double dr[3];
    dr[0] = nagad_a1w_get_derivative(ruser[0]);
    dr[1] = nagad_a1w_get_derivative(ruser[1]);
    dr[2] = nagad_a1w_get_derivative(ruser[2]);

    cout.setf(ios::scientific,ios::floatfield);
    cout.setf(ios::right);
    cout.precision(4);
    cout << "\n Solution, x = ";
    double ans_value = nagad_a1w_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 and tape
    x10ab_a1w_f_(ad_handle,ifail);
    nagad_a1w_ir_remove();
  }

  NAG_FREE(a);
  NAG_FREE(b);
  NAG_FREE(work);

  return exit_status;
}

static void NAG_CALL f_a1w(void* &ad_handle,
                           const Integer& ndim,
                           const nagad_a1w_w_rtype z[],
                           nagad_a1w_w_rtype& fz,
                           Integer iuser[],
                           nagad_a1w_w_rtype ruser[])
{
  // dco/c++ overloading used here to perform AD
  nagad_a1w_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;
}