Comment by yodon

11 hours ago

So excited to see this - the big advantage of 1.58 bits is there are no multiplications at inference time, so you can run them on radically simpler and cheaper hardware.

At 4 bits, you could just have a hard-wired table lookup. Two 4 bit values in, 256 entry table. You can have saturating arithmetic and a post-processing function for free. Somebody must be building hardware like that.

  • Low level software engineers use look up tables.

    Hardware engineers realise that a compiler will almost always find some combination of gates which is smaller/faster than the contents of any table.

  • A LUT is pretty wasteful. You only have a one bit significand, so the mantissa and sign bits are boolean binops, and the exponent is a 2 bit adder.