Fortran code to simulate a discrete-time quantum walk on 1D/2D lattices. Alterable parameters include: size of the lattice, time steps in walk, coin operator, types and scale of unitary errors. It can also be used to simulate a quantum walk search algorithm to find a marked site (as detailed in Kempe, 2003 and Ambainis, 2005). For walks that include random elements, such as noise, multiple walks can be run to obtain averages.