NAG Library Manual, Mark 27.3
```/* D01RJ_T1W_F C++ Header Example Program.
*
* Copyright 2021 Numerical Algorithms Group.
* Mark 27.3, 2021.
*/

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

int main()
{
// Scalars
int exit_status = 0;

cout << "D01RJ_T1W_F C++ Header Example Program Results\n\n";

// The example function can raise various exceptions - it contains
// a division by zero and a log singularity - although its integral
// is well behaved.

Integer exmode[3], exmode_old[3];
nag_get_ieee_exception_mode(exmode_old);
// Save the original halting mode.

// Turn exception halting mode off for the three common exceptions.
for (int i = 0; i < 3; i++)
{
exmode[i] = 0;
}
nag_set_ieee_exception_mode(exmode);

double            pi = X01AAC;
a      = 0.0;
b      = 2.0 * pi;
epsabs = 0.0;
epsrel = 1.0e-4;

Integer            maxsub = 20;
Integer            lrinfo = 80;
Integer            liinfo = 20;
Integer *          iinfo  = 0;

iinfo = new Integer[liinfo];

// Create AD configuration data object
Integer           ifail = 0;

double            inc = 1.0, zero = 0.0;
Integer           iuser[1];
iuser[0]                 = 0;
ruser[0]                 = 4.0 * pi * pi;
ruser[1]                 = 30.0;

const Integer &         nx,
Integer &               iflag)
{
// dco/c++ used here to perform AD of the following
for (int i = 0; i < nx; i++)
{
if (x[i] == 1.0)
{
iflag    = -1;
iuser[0] = iflag;
}
else
{
tmp1  = sqrt(1.0 - x[i] * x[i] / ruser[0]);
tmp2  = x[i] * sin(ruser[1] * x[i]);
fv[i] = tmp2 / tmp1;
}
}
};

// Call the AD routine with first active input derivative incremented
dco::derivative(ruser[0]) = inc;
ifail                     = -1;
rinfo, iinfo, ifail);
dco::derivative(ruser[0]) = zero;
if (ifail < 0)
{
cout << "\n ** nag::ad::d01rj failed error exit ifail = " << ifail << endl;
goto END;
}
// Print inputs and primal outputs.
cout << "\n lower limit of integration (a) = " << dco::value(a) << endl;
cout << " upper limit of integration (b) = " << dco::value(b) << endl;
cout << " absolute accuracy requested    = " << dco::value(epsabs) << endl;
cout << " relative accuracy requested    = " << dco::value(epsrel) << endl;
cout << " maximum number of subintervals = " << maxsub << endl;
cout.setf(ios::scientific, ios::floatfield);
cout.precision(4);
if (ifail >= 0)
{
cout << "\n approximation to the integral  : " << dco::value(result)
<< endl;
cout << " estimate of the absolute error : " << dco::value(abserr) << endl;
cout << " number of function evaluations : " << iinfo[0] << endl;
}

cout << "\n Derivatives calculated: First order tangents\n";
cout << " Computational mode    : algorithmic\n";

// Get derivatives
double dr;
dr = dco::derivative(result);
cout << "\n Derivative of solution w.r.t to parameter in ruser:\n";
cout << " dI/druser[0] = " << dr << endl;

dco::derivative(ruser[1]) = inc;
ifail                     = -1;
rinfo, iinfo, ifail);
dr = dco::derivative(result);
cout << " dI/druser[1] = " << dr << endl;

END:

// Restore the original halting mode
nag_set_ieee_exception_mode(exmode_old);

delete[] rinfo;
delete[] iinfo;
return exit_status;
}
```