Question

The first two steps of the fourth-order Runge-Kutta method finds the value at which point?

(a) At the (n+0.5)^th point

(b) At the (n+1)^th point

(c) At the (n-1)^th point

(d) At the n^th point

I have been asked this question at a job interview.

This intriguing question comes from Transient Flows in portion Transient Flows of Computational Fluid Dynamics

Answer 1

The correct choice is (a) At the (n+0.5)^th point

Explanation: The first two steps of the fourth-order Runge-Kutta method find the values at the (n+0.5)^th point. It does not directly move to the next step. It finds the value at an intermediate point between the current and the next points.