Diffusion Limited Aggregation is an algorithm which was developed in the 80s as a method of simulating physical processes which had diffusion as a primary component, or where it at least plays a major role. Examples of this kind of process are like the deposition of minerals out of solution and some types of dielectric breakdown processes. The update function has the walkers take some number of random steps, and fix their location if they are within some distance of an anchored walker. An easy optimization for this logic is to use bitmap reads for determining neighborhood occupancy instead of iterating through a list.