NAG Library Manual, Mark 29.1
Interfaces:  FL   CL   CPP   AD 

NAG AD Library Introduction
Example description
/* E01DA_P0W_F C++ Header Example Program.
 *
 * Copyright 2023 Numerical Algorithms Group.
 * Mark 29.1, 2023.
 */

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

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

  cout << "E01DA_P0W_F C++ Header Example Program Results\n\n";

  // Skip first line of data file
  string mystr;
  getline(cin, mystr);
  // Read number of x and y data points
  Integer mx, my;
  cin >> mx;
  cin >> my;

  // Allocate arrays for data and interpolant
  double * x = 0, *lamda = 0, *y = 0, *mu = 0, *f = 0, *c = 0, *wrk = 0;
  double * dx = 0, *dy = 0, *df = 0;
  Integer *iwrk = 0;
  Integer  lwrk = (my + 6) * (mx + 6);
  x             = new double[mx];
  y             = new double[my];
  lamda         = new double[mx + 4];
  mu            = new double[my + 4];
  f             = new double[my * mx];
  c             = new double[my * mx];
  wrk           = new double[lwrk];
  dx            = new double[mx];
  dy            = new double[my];
  df            = new double[my * mx];
  iwrk          = new Integer[lwrk];

  // Read data variables
  for (int i = 0; i < mx; i++)
  {
    double xr;
    cin >> xr;
    x[i] = xr;
  }
  for (int i = 0; i < my; i++)
  {
    double yr;
    cin >> yr;
    y[i] = yr;
  }
  for (int i = 0; i < my; i++)
  {
    double fr;
    for (int j = 0; j < mx; j++)
    {
      Integer k = j * my + i;
      cin >> fr;
      f[k] = fr;
    }
  }

  // Call the passive routine
  Integer           px, py;
  Integer           ifail = 0;
  nag::ad::handle_t ad_handle;
  nag::ad::e01da(ad_handle, mx, my, x, y, f, px, py, lamda, mu, c, wrk, ifail);

  const Integer m = 1;
  double        tx[m], ty[m], ff[m];
  tx[0] = 1.4;
  ty[0] = 0.5;

  ifail = 0;
  nag::ad::e02de(ad_handle, m, px, py, tx, ty, lamda, mu, c, ff, wrk, iwrk,
                 ifail);

  cout << "\n Interpolant evaluated at x = " << tx[0];
  cout << " and y = " << ty[0];
  cout.precision(5);
  cout << "\n Value of interpolant        = ";
  cout << ff[0] << endl;

  delete[] x;
  delete[] y;
  delete[] lamda;
  delete[] mu;
  delete[] f;
  delete[] c;
  delete[] wrk;
  delete[] dx;
  delete[] dy;
  delete[] df;
  delete[] iwrk;
  return exit_status;
}