NAG Library Manual, Mark 27.2
Interfaces:  FL   CL   CPP   AD
```/* F03BA_P0W_F C++ Header Example Program.
*
* Copyright 2021 Numerical Algorithms Group.
* Mark 27.2, 2021.
*/

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

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

cout << "F03BA_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;
Integer *ipiv = 0;
a             = new double[n * n];
ipiv          = new Integer[n];

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

// 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);

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

double  d;
Integer id;
ifail = 0;
nag::ad::f03ba(ad_handle, n, a, n, ipiv, d, id, ifail);

cout << "\n d = " << d << " id = " << id << endl;
cout << "\n value of determinant = " << d * pow(2.0, id);
cout << endl;

delete[] a;
delete[] ipiv;

return exit_status;
}
```