 The two sources of error in finite difference methods are round-off error, the loss of precision due to computer rounding of decimal quantities, and truncation error or discretization error, the difference between the exact solution of the original differential equation and the exact quantity assuming perfect arithmetic (that is, assuming no round-off).To use a finite difference method to approximate the solution to a problem, one must first discretize the problem's domain.This is usually done by dividing the domain into a uniform grid (see image to the right).