Hecke operators and the weight distributions of certain codes

We obtain the weight distributions of the Melas and Zetterberg codes and the double error correcting quadratic Goppa codes in terms of the traces of certain Hecke operators acting on spaces of cusp forms for the congruence subgroupΓ1(4) ⊂ SL2(Z). The result is obtained from a description of the weight distributions of the dual codes in terms of class numbers of binary quadratic forms and a combination of the Eichler Selberg Trace Formula with the MacWilliams identities