Complex sentence: Local unimodal sampling (LUS) is a method for doing numerical optimization which does not require the gradient of the problem to be optimized and LUS can hence be used on functions that are not continuous or differentiable.
Split into simpler sentences: Local unimodal sampling (LUS) is an optimization procedure that does not use the gradient of the problem to be optimized. Thus, LUS can be used on functions that are not continuous or differentiable.