Question

What is the condition of stability for the forward Euler method when the function is real?

(a) (Delta tfrac{partial f}{partialphi} <2)

(b) (ig|Delta tfrac{partial f}{partialphi}ig|<2)

(c) Always stable

(d) Never statble

Answer 1

Right choice is (b) (ig|Delta tfrac{partial f}{partialphi}ig|<2)

To explain: The forward Euler method is conditionally stable. For this method to be stable, it needs the following condition to be satisfied.

(ig|1+Delta tfrac{partial f}{partialphi} ig|<1)

When the function f is real, this becomes

(ig|Delta tfrac{partial f}{partialphi} ig|<2).