HIGH-DIMENSION SPARSE GRIDS - Stalking the wild integral Science for Lunch Bunch, 27 June 2007 John Burkardt School of Computational Science Florida State University The integral collects many small items into a single whole. It is the natural way to describe, analyze and simulate geometry, physics, probability, and finance. Although it was 'discovered' as a tool for physical space, it is essential in higher dimensional abstract spaces, particularly in simulation or the analysis of stochastic processes. Approximation techniques must be used for such problems. In high dimensions, every choice we make comes with very high costs. We will discuss the accuracy, efficiency, and flexibility of product rules, Monte Carlo, and Quasi Monte Carlo methods. We will present a sparse grid method that is somewhat like the product rule, with a similar guarantee of accuracy, but at a drastically reduced cost. We will discuss an application involving a stochastic partial differential equation, in which the higher dimensions represent degrees of freedom in the stochastic disturbance.