You can get GAP at http://www.gap-system.org/. We suppose the version of GAP is 4.x. Some functions need the package grape 4.4.
Read my file association_scheme.gap on GAP, Read("association_scheme.gap"). Then you can use the following functions.
We use notations and terminologies in  and . Let R be a relation matrix.
We use the notation for the association scheme with relation matrix R.