/* F03BF_T1W_F C++ Header Example Program.
 *
 * Copyright 2019 Numerical Algorithms Group.
 * Mark 27, 2019.
 */

#include <dco_light.hpp>
#include <nag.h>
#include <nagx04.h>
#include <nagad.h>
#include <stdio.h>
#include <string>
#include <iostream>
using namespace std;

int main(void)
{
  int       exit_status = 0;
  void      *ad_handle = 0;
  Integer   ifail = 0;

  cout << "F03BF_T1W_F C++ Header Example Program Results\n\n";
  // Skip heading in data file
  string mystr;
  getline (cin, mystr);

  // Read problem size and number of right-hand-sides 
  Integer n;
  cin >> n;

  // Allocate arrays containing A and its factorized form, B
  // and the solution X.
  nagad_t1w_w_rtype *a=0, *a_in=0;
  double            *ar=0;
  a    =  new nagad_t1w_w_rtype [n*n];  
  a_in =  new nagad_t1w_w_rtype [n*n];
  ar   =  new double            [n*n];
  
  // Read the matrix A, register and copy
  double dd;
  for (int i = 0; i<n; ++i) {
    for (int j = 0; j<n; ++j) {
      cin >> dd;
      Integer k = i + j*n;
      a_in[k] = dd;
      ar[k] = dd;
    }
  }

  // Print matrix A
  cout << endl;
  NagError  fail;
  INIT_FAIL(fail);
  x04cac(Nag_ColMajor,Nag_LowerMatrix,Nag_NonUnitDiag,n,n,ar,n,
         "  A",0,&fail);

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

  for (int i=0; i<n; i++) {
    for (int j=0; j<=i; j++) {
      Integer k = i + j*n;

      double inc = 1.0;
      nagad_t1w_inc_derivative(&a_in[k],inc);
      
      for (int p=0; p<n; p++) {
        for (int q=0; q<=p; q++) {
          Integer l = p + q*n;
          a[l] = a_in[l];
        }
      }
      
      // Factorize the matrix A
      ifail = 0;
      f07fd_t1w_f_(ad_handle,"L",n,a,n,ifail,1);

      if (i==0 && j==0) {
        // Print Factorization of A
        for (int p = 0; p<n; p++) {
          for (int q = 0; q<=p; q++) {
            int l = p + q*n;
            ar[l] = nagad_t1w_get_value(a[l]);
          }
        }
        cout << endl;
        // NagError  fail;
        INIT_FAIL(fail);
        x04cac(Nag_ColMajor,Nag_LowerMatrix,Nag_NonUnitDiag,n,n,ar,n,
               "  Array A after factorization",0,&fail);
      }
      
      nagad_t1w_w_rtype d;
      Integer           id;
      ifail = 0;
      f03bf_t1w_f_(ad_handle,n,a,n,d,id,ifail);

      if (i==0 && j==0) {
        cout << "\n d = " << nagad_t1w_get_value(d) << " id = " << id << endl;
        cout << "\n value of determinant = ";
        cout << nagad_t1w_get_value(d)*pow(2.0,id) << endl;
      }

      double zero = 0.0;
      nagad_t1w_set_derivative(&a_in[k],zero);

      ar[k] = nagad_t1w_get_derivative(d);
    }
  }
  
  cout << "\n\n Derivatives calculated: First order tangents\n";
  cout << " Computational mode    : algorithmic\n";
  cout << "\n Derivatives of d w.r.t to A:\n";

  // Print derivatives
  cout << endl;
  INIT_FAIL(fail);
  x04cac(Nag_ColMajor,Nag_LowerMatrix,Nag_NonUnitDiag,n,n,ar,n,
         "           d(d)/da(i,j)",0,&fail);

  // Remove computational data object
  ifail = 0;
  x10ab_t1w_f_(ad_handle,ifail);

  delete [] a;
  delete [] a_in;
  delete [] ar;

  return exit_status;
}