Hi everyone,(adsbygoogle = window.adsbygoogle || []).push({});

I've a little problem with my algorithm.

I have two grids: one for time and the other one for the radius.

I need to evaluate this equation:

[tex]\frac{d\beta(r,t)}{dt}=A\beta(r,t)^N[/tex]

I try solving this with a simple Runge Kutta II method, but I'm not convinced at all that this works properly.

Let's check my code:

k1 = deltaT*(-A*beta(i,j-1)**N

k2 = deltaT*(-A*(beta(i,j-1)+k1/2.)**N)

beta(i,j) = beta(i,j-1) + k2

What do you think about that?

This is not the simplest case, just the one you can read in Numerical Recipes ...

P.S.:

beta(i,j) mean beta at r_i and t_j

so i and j referes to radius and time grid respectively

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Problems with Runge-Kutta method

**Physics Forums | Science Articles, Homework Help, Discussion**