NAG Library Manual, Mark 27.3
Interfaces:  FL   CL   CPP   AD
```/* D01TB_P0W_F C++ Header Example Program.
*
* Copyright 2021 Numerical Algorithms Group.
* Mark 27.3, 2021.
*/

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

int main()
{
// Scalars
int     exit_status = 0;
Integer ndim        = 4;

cout << "D01TB_P0W_F C++ Header Example Program Results\n\n";

// Allocate memory
Integer *nptvec = 0;
double * abscis = 0, *weight = 0;
Integer  lwa = 0;

nptvec = new Integer[ndim];
for (int i = 0; i < ndim; i++)
{
nptvec[i] = 4;
lwa       = lwa + nptvec[i];
}
abscis = new double[lwa];
weight = new double[lwa];

// Evaluate primal weights and abscisae in each Dimension
int               j = 0;
nag::ad::handle_t ad_handle;
for (int i = 0; i < ndim; i++)
{

Integer ifail = 0, quadtype = 0;
double  a, b;
switch (i)
{
case 0:
a        = 1.0;
b        = 2.0;
quadtype = 0;
break;
case 1:
a        = 0.0;
b        = 2.0;
quadtype = -3;
break;
case 2:
a        = 0.0;
b        = 0.5;
quadtype = -4;
break;
case 3:
a        = 1.0;
b        = 2.0;
quadtype = -5;
break;
}

nag::ad::d01tb(ad_handle, quadtype, a, b, nptvec[i], &weight[j], &abscis[j],
ifail);
j = j + nptvec[i];
}

auto fun = [&](nag::ad::handle_t &     ad_handle,
const Integer &         ndim,
const double *x,
double &     ret)
{
// dco/c++ overloading used here to perform AD
double            p1 = 6.0, p2 = 8.0;
double r1, r2;
// Split the following function into manageable chunks
// ret = (pow(x[0]*x[1]*x[2],p1)/pow(x[3]+2.0,p2))*
//       exp(-2.0*x[1]-0.5*x[2]*x[2]);
r1  = x[2] * x[2];
r1  = 0.5 * r1;
r2  = -2.0 * x[1];
r1  = r2 - r1;
ret = exp(r1);
r1  = x[0] * x[1] * x[2];
r1  = pow(r1, p1);
r2  = x[3] + 2.0;
r2  = pow(r2, p2);
r2  = r1 / r2;
ret = ret * r2;
return;
};

// Call the passive routine
Integer ifail = 0;
double  ans;
nag::ad::d01fb(ad_handle, ndim, nptvec, lwa, weight, abscis, fun, ans, ifail);

cout.setf(ios::right);
cout.precision(4);
cout << "\n Solution, x = ";
cout.width(12);
cout << ans << endl;

delete[] nptvec;
delete[] abscis;
delete[] weight;
return exit_status;
}
```