turning a simple c++ code into a class (runge kutta method) - c++

Question

I have been extending the simple Runge Kutta example (example 2, 1D ODE) from ODEINT .
The code itself works without trouble.
But then I tried to put everything into a class called runge_kutta and now the recursive inegration is not working anymore, the orginal line is
integrate_adaptive( make_controlled( 1E-12 , 1E-12 , stepper_type() ) ,
rhs , x , 1.0 , 10.0 , 0.1 , write_cout );
I thought that just adding "runge_kutta::"
return integrate_adaptive( make_controlled( 1E-12 , 1E-12 , stepper_type() ) , runge_kutta::rhs, x , 1.0 , 10.0 , timestep , runge_kutta::write_cout );
would fix the issue , but
the error message is
error: no matching function for call to 'integrate_adaptive(boost::numeric::odeint::result_of::make_controlled<boost::numeric::odeint::runge_kutta_dopri5<double> >::type, <unresolved overloaded function type>, double&, double, double, double&, <unresolved overloaded function type>)'
The complete class is defined as follows:
rk.h
#ifndef RK_H_
#define RK_H_
#include <iostream>
#include <cmath>
#include <odeint.hpp>
using namespace boost::numeric::odeint;
class runge_kutta{
public:
runge_kutta(double beta1, double gamma1);
void setparameter(double dist1,double grad);
double solve(double x,double t);
int main();
void write_cout( const double &x , const double t );
private:
void rhs( const double x , double &dxdt , const double t );
double smoothen(double x);
double beta, gamma;
double distance, gradient;
typedef runge_kutta_dopri5< double > stepper_type;
};
#endif /* RK_H_ */
rk.cpp:
#include "rk.h"
double beta, gamma;
double dist, gradient;
void runge_kutta::rhs( const double x , double &dxdt , const double t )
{
dxdt = smoothen(x)*dist*abs(gradient);
}
void runge_kutta::write_cout( const double &x , const double t )
{
std::cout << t << '\t' << x << std::endl;
}
// state_type = double
runge_kutta::runge_kutta(double beta1, double gamma1){
beta = beta1;
gamma = gamma1;
}
void runge_kutta::setparameter(double dist1,double grad){
dist = dist1;
gradient = grad;
}
double runge_kutta::solve(double x,double t){
beta = 0.4;
gamma = 0.8;
typedef runge_kutta_dopri5< double > stepper_type;
return integrate_adaptive( make_controlled( 1E-12 , 1E-12 , stepper_type() ) , runge_kutta::rhs, x , 1.0 , 10.0 , timestep , runge_kutta::write_cout );
}
double runge_kutta::smoothen(double phix){
if (abs(phix)<= beta)
return 1;
else if (abs(phix)> gamma)
return 0;
else
return ((abs(phix)-gamma)*(abs(phix)-gamma)*(2*abs(phix)+gamma-3*beta)/((gamma-beta)*(gamma-beta)*(gamma-beta)));
}

Answer 1

You've replaced functions like write_cout with member functions, but they are not the same thing. You can't just use free functions and member functions interchangeably.
Also, to take the address of a member function you must use &runge_kutta::write_cout not just runge_kutta::write_cout (but that probably won't fix the error, for the reason above).