Specialized software to assist in building models has been developed since the arrival of the first digital computers.
This will direct you either to a peer-reviewed publication or, in some rare cases, to a dedicated Wikipedia page.
[48] System boundaries codes: R = reflecting, A = absorbing, T = transmitting, P = periodic, and I = interacting.
* Algorithm is exact but software produced incorrect results at the time of original table compilation.
† These benchmark run times are not comparable with others due to differing levels of detail.