I am currently attempting to write my own program in maple for the 2nd order Runge-Kutta method for a second order differential equation. What I am finding dfficlut is assigning the initial conditions.  I want to include the condition that

(d(theta)/dt)[0]=v_0 and then proceed to evaluate using different values of v_0, however I'm not allowed to assign a value to a differential.

How do I go about including this condition?

Georgie