Hi everybody,

I ask about a Freefem++ code of a Runge-Kutta schema of order 2 if there is one available somewhere?

I used the following code but it doesn’t work:

// Runge - Kutta Scheme of order 2…

func real [ int ] RK2( real [ int ] u, real t)

{`Preformatted text`

int N=5 ; // The size of vectors

real [ int ] k0 (N), k1 (N), k2 (N); // vectors of size N.

real t1;

real [ int ] uold (N);

uold = 0.;

k0=f(uold, t);

k1 = uold+ k0;

t1 = t + 0.5* dt;

k2 = f(t1,k1);

u=uold+0.5*(k0+k2);

return u ;

}

Thank you in advance.