NAG Library Manual, Mark 27.2
```/* C05RD_P0W_F C++ Header Example Program.
*
* Copyright 2021 Numerical Algorithms Group.
* Mark 27.2, 2021.
*/

#include <iostream>
#include <math.h>
#include <nag.h>
#include <nagx02.h>
#include <nagx04.h>
#include <stdio.h>
#include <string>
using namespace std;

int main(void)
{
// Scalars
int           exit_status = 0;
const Integer n           = 7;

cout << "C05RD_P0W_F C++ Header Example Program Results\n\n";

// problem parameters and starting value
double ruser[5], x[7];

ruser[0] = -1.0;
ruser[1] = 3.0;
ruser[2] = -2.0;
ruser[3] = -2.0;
ruser[4] = -1.0;

for (int i = 0; i < n; ++i)
{
x[i] = -1.0;
}

// Call passive routine
double diag[n], fjac[n * n], factor, fvec[n], qtf[n], r[n * (n + 1) / 2],
rwsav[4 * n + 10], xtol;
Integer irevcm, iwsav[17];

xtol   = sqrt(X02AJC);
factor = 100.0;
for (int i = 0; i < n; ++i)
{
diag[i] = 1.0;
}

Integer ifail = 0, mode = 2;
irevcm            = 0;
do
{
factor, r, qtf, iwsav, rwsav, ifail);

switch (irevcm)
{
case 1:
// Monitoring exit
continue;
case 2:
for (int i = 0; i < n; ++i)
{
fvec[i] = (ruser[1] + ruser[2] * x[i]) * x[i] - ruser[4];
}
for (int i = 1; i < n; ++i)
{
fvec[i] = fvec[i] + ruser[0] * x[i - 1];
}
for (int i = 0; i < n - 1; ++i)
{
fvec[i] = fvec[i] + ruser[3] * x[i + 1];
}
break;
case 3:
for (int i = 0; i < n * n; ++i)
{
fjac[i] = 0.0;
}
fjac[0] = ruser[1] + 2.0 * ruser[2] * x[0];
fjac[n] = ruser[3];
for (int i = 1; i < n - 1; ++i)
{
int k       = i * n + i;
fjac[k - n] = ruser[0];
fjac[k]     = ruser[1] + 2.0 * ruser[2] * x[i];
fjac[k + n] = ruser[3];
}
fjac[n * n - n - 1] = ruser[0];
fjac[n * n - 1]     = ruser[1] + 2.0 * ruser[2] * x[n - 1];
break;
}
}
while (irevcm != 0);

cout.setf(ios::scientific, ios::floatfield);
cout.precision(3);
cout << "           Solution:\n";
for (int i = 0; i < n; ++i)
{
cout.width(8);
cout << i + 1;
cout.width(18);
cout << x[i] << endl;
}

return exit_status;
}
```