/* D01FB_T1W_F C++ Header Example Program.
 *
 * Copyright 2021 Numerical Algorithms Group.
 * Mark 27.2, 2021.
 */

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

extern "C"
{
  static void NAG_CALL fun(void *&                 ad_handle,
                           const Integer &         ndim,
                           const nagad_t1w_w_rtype x[],
                           nagad_t1w_w_rtype &     ret,
                           Integer                 iuser[],
                           nagad_t1w_w_rtype       ruser[]);
}

int main(void)
{
  // Scalars
  int     exit_status = 0;
  Integer ndim        = 4;

  cout << "D01FB_T1W_F C++ Header Example Program Results\n\n";

  // Allocate memory
  Integer *          nptvec = 0;
  nagad_t1w_w_rtype *abscis = 0, *weight = 0;
  Integer            lwa = 0;

  nptvec = new Integer[ndim];
  for (int i = 0; i < ndim; i++)
    {
      nptvec[i] = 4;
      lwa       = lwa + nptvec[i];
    }
  abscis = new nagad_t1w_w_rtype[lwa];
  weight = new nagad_t1w_w_rtype[lwa];

  // Create AD configuration data object
  Integer ifail     = 0;
  void *  ad_handle = 0;
  nag::ad::x10aa(ad_handle, ifail);

  // Evaluate primal weights and abscisae in each dimension
  int j = 0;
  for (int i = 0; i < ndim; i++)
    {

      Integer           ifail = 0, quadtype = 0;
      nagad_t1w_w_rtype a, b;
      switch (i)
        {
        case 0:
          a        = 1.0;
          b        = 2.0;
          quadtype = 0;
          break;
        case 1:
          a        = 0.0;
          b        = 2.0;
          quadtype = -3;
          break;
        case 2:
          a        = 0.0;
          b        = 0.5;
          quadtype = -4;
          break;
        case 3:
          a        = 1.0;
          b        = 2.0;
          quadtype = -5;
          break;
        }
      nag::ad::d01tb(ad_handle, quadtype, a, b, nptvec[i], &weight[j],
                     &abscis[j], ifail);
      j = j + nptvec[i];
    }

  // Call the AD routine
  ifail = 0;
  nagad_t1w_w_rtype ans;
  nagad_t1w_w_rtype ruser[1];
  Integer           iuser[1];
  nag::ad::d01fb(ad_handle, ndim, nptvec, lwa, weight, abscis, fun, ans, -1,
                 iuser, -1, ruser, ifail);

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

  // Get derivatives
  cout.setf(ios::right);
  cout.precision(4);
  cout << "\n Solution, x = ";
  double ans_value = dco::value(ans);
  cout.width(12);
  cout << ans_value << endl;
  cout << " Derivatives:\n";
  cout << " dim   j  d/dweight    d/dabscis\n";

  cout.setf(ios::scientific, ios::floatfield);

  j = -1;
  for (int i = 0; i < ndim; i++)
    {
      for (int k = 1; k <= nptvec[i]; k++)
        {

          j          = j + 1;
          double inc = 1.0, zero = 0.0;

          dco::derivative(weight[j]) = inc;
          nag::ad::d01fb(ad_handle, ndim, nptvec, lwa, weight, abscis, fun, ans,
                         -1, iuser, -1, ruser, ifail);
          double w                   = dco::derivative(ans);
          dco::derivative(weight[j]) = zero;

          dco::derivative(abscis[j]) = inc;
          nag::ad::d01fb(ad_handle, ndim, nptvec, lwa, weight, abscis, fun, ans,
                         -1, iuser, -1, ruser, ifail);
          double a                   = dco::derivative(ans);
          dco::derivative(abscis[j]) = zero;

          if (k == 1)
            {
              cout.width(4);
              cout << i;
            }
          else
            {
              cout << "    ";
            }
          cout.width(8);
          cout << k;
          cout.width(12);
          cout << w;
          cout.width(12);
          cout << a << endl;
        }
    }

  // Remove computational data object
  nag::ad::x10ab(ad_handle, ifail);

  delete[] nptvec;
  delete[] abscis;
  delete[] weight;
  return exit_status;
}
static void NAG_CALL fun(void *&                 ad_handle,
                         const Integer &         ndim,
                         const nagad_t1w_w_rtype x[],
                         nagad_t1w_w_rtype &     ret,
                         Integer                 iuser[],
                         nagad_t1w_w_rtype       ruser[])
{
  // dco/c++ overloading used here to perform AD
  double            p1 = 6.0, p2 = 8.0;
  nagad_t1w_w_rtype r1, r2;
  // Split the following function into manageable chunks
  // ret = (pow(x[0]*x[1]*x[2],p1)/pow(x[3]+2.0,p2))*
  //       exp(-2.0*x[1]-0.5*x[2]*x[2]);
  r1  = x[2] * x[2];
  r1  = 0.5 * r1;
  r2  = -2.0 * x[1];
  r1  = r2 - r1;
  ret = exp(r1);
  r1  = x[0] * x[1] * x[2];
  r1  = pow(r1, p1);
  r2  = x[3] + 2.0;
  r2  = pow(r2, p2);
  r2  = r1 / r2;
  ret = ret * r2;
  return;
}