Hi, my discovery tour of new gretl functions goes on - thanks for adding the conv2d function! However, I think the documentation needs to be adapted to the new situation. For example, in section 18.3 of the guide (Neat tricks) the convolution is described. It still says there that "There's no dedicated function to do that". However, now conv2d(p,q) now does that (as a special 1d-case I guess) and produces exactly the needed outcome. The function reference for conv2d itself could be a little more explicit. For example it could mention exactly this special case of vectors as inputs and the relationship with polynomial multiplication. (About 2d-convolution I'm not sure if perhaps there exist slightly different definitions or conventions? If so, a precise reference would also help.) thanks sven