- #1
ognik
- 643
- 2
Hi - trying to write a Fortran95 program to solve a trivial 1st order DE (dy/dx=-xy), the idea being that once it works it can be used for different forms of f(x,y). I use Euler to get the starting point, then A-B's 2 step formula for the next 2 starting points. It is when I apply the A-B 4-step formula that I get obviously wrong values for Y(n+1) (using debug to compare with expected values). I've looked at this every which way until my head hurts, can't see what I'm doing wrong in the program? (code in attached zip file)