```/* E04DG_P0W_F C++ Header Example Program.
*
* Copyright 2019 Numerical Algorithms Group.
* Mark 27, 2019.
*/

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

extern "C"
{
static void NAG_CALL objfun(void* &ad_handle, Integer &mode,
const Integer &n, const double x[],
double &objf, double objgrd[],
const Integer &nstate, Integer iuser[],
double ruser[]);
}

int main(void)
{
int     exit_status = 0;
double  objf;
cout << "E04DG_P0W_F C++ Header Example Program Results\n\n";

Integer ifail = 0;

// Read problem parameters and register for differentiation
// Skip first line of data file
string mystr;
getline (cin, mystr);

Integer n;
cin >> n;

// passive routine fixed length array arguments
Integer        iuser[1], iwsav[610];
double         ruser[1], rwsav[475];
char           cwsav[1];
logical        lwsav[120];
const Charlen  name_l = 6, cwsav_l = 1;

// passive routine variable length arrays
Integer        *iwork = 0;
double         *x = 0, *x_in = 0, *objgrd = 0, *work = 0;

iwork  = new Integer [n+1];
x      = new double  [n];
x_in   = new double  [n];
objgrd = new double  [n];
work   = new double  [13*n];

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

// Initialize sav arrays
ifail = 0;
e04wb_p0w_f_("E04DGA",cwsav,1,lwsav,120,iwsav,610,rwsav,475,ifail,name_l,
cwsav_l);

// Solve the problem
Integer iter;
ifail = 0;
ruser,lwsav,iwsav,rwsav,ifail);

// Primal results
cout.setf(ios::scientific,ios::floatfield);
cout.precision(3);
cout << "\n Objective value = ";
cout.width(12); cout << objf;
cout << "\n Solution point  = ";
for (int i=0; i<n; i++) {
cout.width(12); cout << x[i];
}

cout << "\n Estim gradient  = ";
for (int i=0; i<n; i++) {
cout.width(12); cout << objgrd[i];
}

delete [] iwork;
delete [] x;
delete [] x_in;
delete [] objgrd;
delete [] work;
return exit_status;
}

static void NAG_CALL objfun(void* &ad_handle, Integer &mode,
const Integer &n, const double x[],
double &objf, double objgrd[],
const Integer &nstate, Integer iuser[],
double ruser[])
{

double  x1, x2, y1, y2, expx1;

x1 = x[0];
x2 = x[1];
expx1 = exp(x1);
y1 = 2.0*x1;
y1 = y1 + x2;
y2 = x2 + 1.0;
x1 = y1*y1;
x2 = y2*y2;
x1 = x1 + x2;
objf = expx1*x1;

if (mode==2) {
y2 = y1 + y2;
y2 = 2.0*y2;
y1 = 4.0*y1;
y1 = expx1*y1;
objgrd[0] = y1 + objf;
objgrd[1] = expx1*y2;
}

return;
}
```