Algorithm 1: Simulation summary

// Let N(t,i,j) represent the neutron density at time t at grid position (i,j).

// Initial conditions
for all grid positions (i,j)
  N(0,i,j) = 0 if not at center of grid
  N(0,i,j) = 10^7 at center of grid

for each time step t,
  for all grid positions (i,j) (except the outside boundary)
    N(t+1,i,j) = stencil(i,j)
  // Boundary conditions
  N(t+1,boundary) = 0
  Inspect the simulation if desired.
endfor