An efficient algorithm is presented for inverting matrices which are p
eriodically Toeplitz, i.e., whose diagonal and subdiagonal entries exh
ibit periodic repetitions. Such matrices are not per symmetric and thu
s cannot be inverted by Trench's method. An alternative approach based
on appropriate matrix factorization and partitioning is suggested. Th
e algorithm provides certain insight on the formation of the inverse m
atrix, is implementable on a set of circularly pipelined processors an
d, as a special case, can be used for inverting a set of block Toeplit
z matrices without requiring any matrix operation.