Runge Kutta

[ramye]

hello, I'm looking for someone to help me with this code..
i'm trying to resolve a second order equation..
(dv/dt)= 10 - (94.5/0.3)x - (13/0.3)v;
(dx/dt)=v;

this is what i have written so far, i think it's not bad i have one simple problem calling the RK (Runge Kutta) function
error : " reference to non-static function must be called "




#include<iostream>
#include<math.h>
#include<cmath>
using namespace std;


double RK(double (*f)(double a,double b),double t1,double t0,double x0){
double K1=f(t0,x0);
double dt=t1-t0;
double K2=f(t0+dt/2,x0+(dt/2)*K1);
double K3=f(t0+dt,x0+dt*K2);
return x0+(dt/6)*(K1+4*K2+K3);
}


class RKI{
public:
double v0;
double t0;
double x0;

RKI(){
x0=v0=t0=0;
}


double F_V(double t0,double v0){
return 10-(94.5/0.3)*x0-(13/0.3)*v0;
}

double F_X(double t0,double x0){
return v0;
}



};


int main(){
RKI r;
double x1;
double v1;
double t1;
for(int i=0;i<10;++i){
t1=r.t0+0.2;
v1=RK(r.F_V,t1,r.t0,r.v0); // Error here
x1=RK(r.F_X,t1,r.t0,r.x0); // Error here
cout<<"v1 = "<<v1<<endl;
cout<<"x1 = "<<x1<<endl;
cout<<"t1 = "<<t1<<endl;
r.x0=x1;
r.v0=v1;
r.t0=t1;
}
return 0;
}


Thank you for your help!

[ats15]

http://stackoverflow.com/questions/12662891/c-passing-member-function-as-argument