The stability of the circular deconvolution algorithm for the solution of a
circulant linear system is studied. This algorithm is known to be not stro
ngly stable. The notion of almost strong stability is introduced, and it is
shown that it leads to results similar to those for strongly stable algori
thms. Then it is proved that the circular deconvolution algorithm based on
fast Fourier transforms is almost strongly stable with respect to the 2-nor
m. A numerical example illustrates the theoretical conclusions.