This formula can be used to compute norms of arbitrary finitely supported convolution operators on the free group. Essentially the same technique yields a formula for the norms of sums of matrix ...

Mathematics of Computation, Vol. 31, No. 139 (Jul., 1977), pp. 733-737 (5 pages) An attainable bound for the infinity norm of the inverse of a whole class of symmetric circulant Toeplitz matrices is ...