#include <iostream.h>
#include <math.h>
#include <cfortran/cfortran.h>

extern "C" {
  void  fcn(int npar, double grad[2], double * fcnval,
          double xval[2], int iflag, void * futil);
           }

FCALLSCSUB6(fcn,FCN,fcn,INT,DOUBLEV,PDOUBLE,DOUBLEV,INT,ROUTINE)

extern "C" void fcn(int npar, double grad[2], double * fcnval, 
double par[2], int iflag, void * futil)
{

  extern int num_points;
  extern double z[], n[];

  double r = 0.52e-6;                      // m
  double DeltaRho = 63.0;                  // kg / m^3
  double g = 9.80;                         // m / s^2
  double T = 293.0;                        // K
  double PI = 3.14159265;
  double A = - 4.*PI*pow(r,3)*g*DeltaRho/(3.*T);
  double nu0 = par[0];
  double k  = par[1]* 1.0e-23;              // k in J/K
  double logL = 0.;
  for(int i =0; i<num_points; i++)
  {
    double nu = nu0 * exp ( A * z[i]*1.0e-6 / k );   // convert z to meters
    logL = logL + n[i]*log(nu) - nu;
  }
  *fcnval = -2.*logL;

}