NAG Library Manual, Mark 29.3
Interfaces:  FL   CL   CPP   AD 

NAG AD Library Introduction
Example description
/* F07FE_P0W_F C++ Header Example Program.
 *
 * Copyright 2023 Numerical Algorithms Group.
 * Mark 29.3, 2023.
 */

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

int main()
{
  int               exit_status = 0;
  nag::ad::handle_t ad_handle;
  Integer           ifail = 0;

  cout << "F07FE_P0W_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, nrhs;
  cin >> n;
  cin >> nrhs;

  // Allocate arrays containing A and its factorized form, B
  // and the solution X.
  double *a = 0, *b = 0;
  a = new double[n * n];
  b = new double[n * nrhs];

  // Read the lower triangular matrix A, register and copy
  double dd;
  for (int i = 0; i < n; ++i)
  {
    for (int j = 0; j <= i; ++j)
    {
      int k = i + j * n;
      cin >> a[k];
    }
  }
  // Read the right-hand-sides, register and copy
  for (int i = 0; i < n; ++i)
  {
    for (int j = 0; j < nrhs; ++j)
    {
      int k = i + j * n;
      cin >> b[k];
    }
  }

  // Factorize the matrix A
  ifail = 0;
  nag::ad::f07fd(ad_handle, "L", n, a, n, ifail);

  // Solve the system
  ifail = 0;
  nag::ad::f07fe(ad_handle, "L", n, nrhs, a, n, b, n, ifail);

  // Print solution
  cout << endl;
  NagError fail;
  INIT_FAIL(fail);
  x04cac(Nag_ColMajor, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, b, n,
         "  Solution", 0, &fail);

  delete[] a;
  delete[] b;
  return exit_status;
}