# list manipulation – Convolution for large arrays

I am trying to use $$texttt{ListConvolve(a, b, {1, -1}, 0)}$$ for large arrays $$texttt{a}$$ and $$texttt{b}$$ (2048 length) to fast-up the polynomial multiplication. The problem is that I get a wrong answer each time!

I tried the following list enter link description here for $$texttt{a}=texttt{b}$$, where I should obtain $$5.75044*10^-70$$ as a first term after the convolution is done, but it didn’t work!