/* D01RK_A1W_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 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 << "D01RK_A1W_F C++ Header Example Program Results\n\n";

  // Create AD tape
  dco::ga1s<double>::global_tape = dco::ga1s<double>::tape_t::create();

  Integer           key = 6;
  double            pi  = X01AAC;
  nagad_a1w_w_rtype a, b, epsabs, epsrel;
  a      = 0.0;
  b      = 2.0 * pi;
  epsabs = 0.0;
  epsrel = 1.0e-4;

  Integer            maxsub = 20;
  Integer            lrinfo = 80;
  Integer            liinfo = 20;
  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;
  nag::ad::x10aa(ad_handle, ifail);

  double            inc = 1.0;
  nagad_a1w_w_rtype result, abserr, ruser[2];
  Integer           iuser[1];
  const void *      cpuser = 0;
  iuser[0]                 = 0;
  ruser[0]                 = 30.0;
  ruser[1]                 = 1.0;

  // Register variables to differentiate w.r.t.
  dco::ga1s<double>::global_tape->register_variable(ruser[0]);
  dco::ga1s<double>::global_tape->register_variable(ruser[1]);

  // Call the AD routine
  ifail = -1;
  nag::ad::d01rk(ad_handle, f, a, b, key, epsabs, epsrel, maxsub, result,
                 abserr, rinfo, iinfo, -1, iuser, -1, ruser, cpuser, ifail);
  if (ifail < 0)
    {
      cout << "\n ** nag::ad::d01rk failed error exit ifail = " << ifail
           << endl;
      goto END;
    }
  // Print inputs and primal outputs.
  cout << "\n lower limit of integration (a) = " << dco::value(a) << endl;
  cout << " upper limit of integration (b) = " << dco::value(b) << endl;
  cout << " choice of Gaussian rule (key)  = " << key << endl;
  cout << " absolute accuracy requested    = " << dco::value(epsabs) << endl;
  cout << " relative accuracy requested    = " << dco::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  : " << dco::value(result)
           << endl;
      cout << " estimate of the absolute error : " << dco::value(abserr)
           << endl;
      cout << " number of function evaluations : " << iinfo[0] << endl;
    }

  // Setup evaluation of derivatives via adjoints.
  dco::derivative(result) += inc;
  ifail                                              = 0;
  dco::ga1s<double>::global_tape->sparse_interpret() = true;
  dco::ga1s<double>::global_tape->interpret_adjoint();

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

  // Get derivatives
  double dr;
  dr = dco::derivative(ruser[0]);
  cout << "\n Derivative of solution w.r.t to parameter in ruser:\n";
  cout << " dI/druser[0] = " << dr << endl;
  dr = dco::derivative(ruser[1]);
  cout << " dI/druser[1] = " << dr << endl;

END:
  // Remove computational data object and tape
  nag::ad::x10ab(ad_handle, ifail);
  dco::ga1s<double>::tape_t::remove(dco::ga1s<double>::global_tape);

  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
  for (int i = 0; i < nx; i++)
    {
      fv[i] = x[i] * sin(ruser[0] * x[i]) * cos(ruser[1] * x[i]);
    }
  return;
}