hi there, I've used rk4.f90 for backwards integration of a first order Differential equation successfully with a negative step size. My problem now is that I would like to use the odeint.f90 routine to do the same thing. It just doesn't work with x2<x1, I've already tried using negatives h1 and hmin step sizes.
Any Ideas???

Any help is appreciated, thanks

Hi;

Sub Odeint() starts by transfering the sign of (X2-X1) to the 1st step to be attempted, H1.
So, X2<X1 and +ve H1 should be OK.
Could you elaborate on: " ... odeint just doesn't work"??

Monir