NAG Library Manual, Mark 28.5
Interfaces:  FL   CL   CPP   AD 

NAG AD Library Introduction
Example description
/* F07AJ_P0W_F C++ Header Example Program.
 *
 * Copyright 2022 Numerical Algorithms Group.
 * Mark 28.5, 2022.
 */

#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 << "F07AJ_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;
  cin >> n;

  // Allocate arrays containing A and its factorized form, B
  // and the solution X.
  double * a = 0, *work = 0;
  Integer *ipiv  = 0;
  Integer  lwork = 64 * n;
  a              = new double[n * n];
  work           = new double[lwork];
  ipiv           = new Integer[n];

  // Read the matrix A, register and copy
  for (int i = 0; i < n; ++i)
  {
    for (int j = 0; j < n; ++j)
    {
      Integer k = i + j * n;
      cin >> a[k];
    }
  }

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

  // Factorize the matrix A
  ifail = 0;
  nag::ad::f07ad(ad_handle, n, n, a, n, ipiv, ifail);

  // Invert A
  ifail = 0;
  nag::ad::f07aj(ad_handle, n, a, n, ipiv, work, lwork, ifail);

  // Print Inverse
  cout << endl;
  x04cac(Nag_ColMajor, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n, a, n,
         "  Inverse", 0, &fail);

  delete[] a;
  delete[] work;
  delete[] ipiv;
  return exit_status;
}