I've been clumsily exploring the space of what kind of DSP you can do without multipliers, because (in hardware) multiplication is one or two orders of magnitud

I've been clumsily exploring the space of what kind of DSP you can do without multipliers, because (in hardware) multiplication is one or two orders of magnitude more expensive than addition; see https://nbviewer.org/url/canonical.org/~kragen/sw/dev3/sparse-gabor.ipynb https://nbviewer.org/url/canonical.org/~kragen/sw/dev3/spars... for one example.