Need some help with Runge Kutta in c++

[lastchance]

Please:
- put your code sample within code tags, so that we can see the structure more easily.
- tell us what the input should be;
- tell us why you think the output is "weird".


This line:
tou = pow(a, 3/2);
doesn't do what you think it does, because of integer division. However, I doubt that has much to do with your problem.


0.01 is presumably your timestep - don't hard-code it. Put it in a variable so that it only needs changing once, not a myriad of times.


Don't write lines like
F[3] = AU * r_y[j]/pow(rad, 3.0) * -1;
The minus sign can just go in front; it doesn't require a multiplication by -1.


And here ... I'll hazard a guess that those j ... should be i. Occurs several times.

r_x[j] = temp[0];
r_y[j] = temp[1];
v_x[j] = temp[2];
v_y[j] = temp[3];

[deleted account xyzzy]

Hmmmm, did the OP do a vanishing act?

Yet again someone trying to help ends up looking like they are talking to themselves.

[Ganado]

Whoever did that is a POS, there was nothing wrong with the OP other than bad formatting.