/* E01AA_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>
#include <string>
using namespace std;

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

  cout << "E01AA_A1W_F C++ Header Example Program Results\n\n";

  // Skip first line of data file
  string mystr;
  getline(cin, mystr);
  // Read number of data points
  Integer n;
  cin >> n;

  // Allocate arrays for data and interpolant
  nagad_a1w_w_rtype x, *a = 0, *b = 0, *c = 0;
  double            xr, ar;
  Integer           n1, n2;
  n1 = n + 1;
  n2 = n * (n + 1) / 2;
  if (!(a = NAG_ALLOC(n1, nagad_a1w_w_rtype)) ||
      !(b = NAG_ALLOC(n1, nagad_a1w_w_rtype)) ||
      !(c = NAG_ALLOC(n2, nagad_a1w_w_rtype)))
    {
      printf("Allocation failure\n");
      exit_status = -1;
    }
  if (exit_status == 0)
    {
      // Create AD tape
      dco::ga1s<double>::global_tape = dco::ga1s<double>::tape_t::create();

      cin >> xr;
      x = xr;

      for (int i = 0; i < n1; i++)
        {
          cin >> ar;
          a[i] = ar;
        }
      for (int i = 0; i < n1; i++)
        {
          cin >> ar;
          b[i] = ar;
        }

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

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

      // Register variables to differentiate w.r.t.
      for (int i = 0; i < n1; i++)
        {
          dco::ga1s<double>::global_tape->register_variable(a[i]);
        }

      // Call the AD routine
      ifail = 0;
      nag::ad::e01aa(ad_handle, a, b, c, n, x, ifail);

      cout.setf(ios::scientific, ios::floatfield);
      cout.precision(5);
      cout << "\n Interpolation point = ";
      cout.width(12);
      cout << xr << endl;
      cout << "\n Function value at interpolation point = ";
      cout.width(12);
      cout << dco::value(c[n2 - 1]) << endl;

      // Setup evaluation of derivatives via adjoints.
      double inc = 1.0;
      dco::derivative(c[n2 - 1]) += 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
      cout << "\n Derivatives of fitted value w.r.t. x values:\n";
      cout << "  j         d/da(j)\n";
      for (int j = 0; j < n1; j++)
        {
          double dx = dco::derivative(a[j]);
          cout.width(3);
          cout << j + 1 << "     ";
          cout.width(12);
          cout << dx << endl;
        }

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