/* C05QS_P0W_F C++ Header Example Program.
 *
 * Copyright 2019 Numerical Algorithms Group.
 * Mark 27, 2019.
 */

#include <nag.h>
#include <nagad.h>
#include <stdio.h>
#include <math.h>
#include <nagx02.h>
#include <nagx04.h>
#include <iostream>
#include <string>
using namespace std;

extern "C"
{
  static void (NAG_CALL fcn)(void* &ad_handle,
                             const Integer &n,
                             const Integer &lindf,
                             const Integer indf[],
                             const double x[],
                             double fvec[],
                             Integer iuser[],
                             double ruser[],
                             Integer &iflag);
}

int main (void)
{
  // Scalars
  int               exit_status = 0;
  const Integer     n = 7, lrcomm = 12 + 3*n, licomm = 8*n + 19 + 3*n;

  cout << "C05QS_P0W_F C++ Header Example Program Results\n\n";

  // problem parameters and starting value
  double ruser[5], x[7];

  ruser[0] = -1.0;
  ruser[1] =  3.0;
  ruser[2] = -2.0;
  ruser[3] = -2.0;
  ruser[4] = -1.0;

  for (int i=0; i<n; ++i) {
    x[i] = -1.0;
  }

  Integer ifail = 0;
  void    *ad_handle = 0;
  double  fvec[n], rcomm[lrcomm], xtol;
  Integer icomm[licomm], iuser[1];
  logical init = Nag_TRUE;

  xtol = sqrt(X02AJC);

  c05qs_p0w_f_(ad_handle,fcn,n,x,fvec,xtol,init,rcomm,lrcomm,icomm,
               licomm,iuser,ruser,ifail);

  cout.setf(ios::scientific,ios::floatfield);
  cout.precision(4);
  cout << "           Solution:\n";
  for (int i=0; i<n; ++i) {
    cout.width(10);
    cout << i+1;
    cout.width(20);
    cout << x[i] << endl;
  }

  return exit_status;
}

static void (NAG_CALL fcn)(void* &ad_handle,
                           const Integer &n,
                           const Integer &lindf,
                           const Integer indf[],
                           const double x[],
                           double fvec[],
                           Integer iuser[],
                           double ruser[],
                           Integer &iflag)
{
  for (int ind=0; ind<lindf; ++ind) {
    int i = indf[ind] - 1;
    fvec[i] = (ruser[1] + ruser[2]*x[i])*x[i] - ruser[4];
    if (i>0) fvec[i] = fvec[i] + ruser[0]*x[i-1];
    if (i<n-1) fvec[i] = fvec[i] + ruser[3]*x[i+1];
  }
  iflag = 0;
  return;
}