For given A/B returns conv(A,B) (non-circular). Subroutine can automatically

choose between three implementations: straightforward O(M*N) formula for

very small N (or M), overlap-add algorithm for cases where max(M,N) is

significantly larger than min(M,N), but O(M*N) algorithm is too slow, and

general FFT-based formula for cases where two previois algorithms are too

slow.- For given A/B returns conv(A,B) (non-circular). Subroutine can automatically

choose between three implementations: straightforward O(M*N)　formula　for

very small N (or M), overlap-add algorithm for　cases　where　max(M,N)　is

significantly larger than min(M,N), but O(M*N) algorithm is too slow,　and

general FFT-based formula for cases where two previois algorithms are　too

slow.