On the multiplication of scalar and matrix power series with integer coefficients
A. S. Buslenko, Х. Д. Икрамов · Moscow University Computational Mathematics and Cybernetics · 2008
It is shown that, in Mathematica 5, the exact product of power series whose coefficients are integers or integer matrices can be calculated significantly faster if, instead of the library function for this product, one uses number-theoretic transforms, which are analogues of the fast Fourier transform in the ring of integers Z.