/* D02BJ_A1W_F C++ Header Example Program.
 *
 * Copyright 2020 Numerical Algorithms Group.
 *
 * Mark 27.1, 2020.
 *
 */

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

#ifdef __cplusplus
extern "C"
{
#endif
  static void NAG_CALL fcn(void * &ad_handle, const nagad_a1w_w_rtype &x,
                           const nagad_a1w_w_rtype y[], nagad_a1w_w_rtype f[],
                           Integer iuser [], nagad_a1w_w_rtype ruser[]);
  static void NAG_CALL g(void * &ad_handle, const nagad_a1w_w_rtype &x,
                         const nagad_a1w_w_rtype y[],
                         nagad_a1w_w_rtype &retval, Integer iuser [],
                         nagad_a1w_w_rtype ruser[]);
#ifdef __cplusplus
}
#endif

int main(void)
{
  int               exit_status = 0;
  const Integer     n = 3;

  cout << "D02BJ_A1W_F C++ Header Example Program Results\n\n";

  Integer           iw, iuser[1];
  double            pi;
  nagad_a1w_w_rtype tol, x, xinit, xend, ruser[2];
  nagad_a1w_w_rtype *y = 0, *yinit = 0, *w = 0;

  iw = 20*n;
  w     = new nagad_a1w_w_rtype [iw];
  y     = new nagad_a1w_w_rtype [n];
  yinit = new nagad_a1w_w_rtype [n];

  xinit = 0.0;
  xend = 10.0;
  pi = nag_math_pi;
  
  cout << "\n\nCase: no intermediate output, root-finding\n";
  const double tolr = 1.0e-5;
  tol = tolr;
  cout << "\n  Calculation with tol = " << tolr << endl;

  // Create AD tape
  nagad_a1w_ir_create();

  // Create AD configuration data object
  Integer ifail = 0;
  void    *ad_handle = 0;
  x10aa_a1w_f_(ad_handle,ifail);

  yinit[0] = 0.5;
  yinit[1] = 0.5;
  yinit[2] = 0.2*pi;

  x = xinit;
  const double alpha = -0.032;
  const double beta = -0.02;
  ruser[0] = alpha;
  ruser[1] = beta;

  // Register variables to differentiate w.r.t.
  nagad_a1w_ir_register_variable(&ruser[0]);
  nagad_a1w_ir_register_variable(&ruser[1]);
  nagad_a1w_ir_register_variable(&yinit[0]);
  nagad_a1w_ir_register_variable(&yinit[1]);
  nagad_a1w_ir_register_variable(&yinit[2]);

  y[0] = yinit[0];
  y[1] = yinit[1];
  y[2] = yinit[2];

  ifail = 0;
  d02bj_a1w_f_(ad_handle,x,xend,n,y,fcn,tol,"D", d02bj_a1w_x_, g,
               w,iuser,ruser,ifail,1);

  cout.setf(ios::fixed);
  cout.setf(ios::right);
  cout.precision(3);
  cout << "\n  Root of Y(1) = 0.0 at ";
  cout.width(5); cout << x << endl;
  cout << "\n  Solution is  ";
  cout.precision(4);
  for (int i = 0; i < 3; ++i) {
    cout.width(10); cout << y[i];
  }
  cout << endl;

  // Setup evaluation of derivatives via adjoints.
  double inc = 1.0;
  nagad_a1w_inc_derivative(&x,inc);
  ifail = 0;
  nagad_a1w_ir_interpret_adjoint(ifail);

  cout << "\n Derivatives calculated: First order adjoints\n";
  cout << " Computational mode    : algorithmic\n";
  
  // Get derivatives
  cout << "\n Derivatives: (hit point w.r.t. parameters)\n";
  cout.setf(ios::scientific,ios::floatfield);
  cout.precision(5);
  double dr;
  dr = nagad_a1w_get_derivative(ruser[0]);
  cout << "     dx/dg      = ";
  cout.width(12); cout << -dr << endl;
  dr = nagad_a1w_get_derivative(ruser[1]);
  cout << "     dx/ddrag   = ";
  cout.width(12); cout << -dr << endl;
  dr = nagad_a1w_get_derivative(yinit[0]);
  cout << "     dx/dheight = ";
  cout.width(12); cout << dr << endl;
  dr = nagad_a1w_get_derivative(yinit[1]);
  cout << "     dx/dvel    = ";
  cout.width(12); cout << dr << endl;
  dr = nagad_a1w_get_derivative(yinit[2]);
  cout << "     dx/dangle  = ";
  cout.width(12); cout << dr << endl;

  x10ab_a1w_f_(ad_handle,ifail);
  nagad_a1w_ir_remove();

  delete [] w;
  delete [] y;
  delete [] yinit;
  return exit_status;
}

static void NAG_CALL fcn(void * &ad_handle, const nagad_a1w_w_rtype &x,
                         const nagad_a1w_w_rtype y[], nagad_a1w_w_rtype f[],
                         Integer iuser [], nagad_a1w_w_rtype ruser[])
{
  nagad_a1w_w_rtype alpha, beta;
  alpha = ruser[0];
  beta = ruser[1];

  f[0] = tan(y[2]);
  f[1] = alpha*tan(y[2])/y[1] + beta*y[1]/cos(y[2]);
  f[2] = alpha/(y[1]*y[1]);
}

static void NAG_CALL g(void * &ad_handle, const nagad_a1w_w_rtype &x,
                       const nagad_a1w_w_rtype y[],
                       nagad_a1w_w_rtype &retval,
                       Integer iuser [], nagad_a1w_w_rtype ruser[])
{
  retval = y[0];
}