alt Hacker News> Booth's idea is to rewrite one of the inputs in base (usually) "4", except that the digits go from -2 to +2 instead of 0 to 3.
That's base 5 then. It needs to go from -2 to +1 if you want base 4
> Booth's idea is to rewrite one of the inputs in base (usually) "4", except that the digits go from -2 to +2 instead of 0 to 3.
That's base 5 then. It needs to go from -2 to +1 if you want base 4
It's still a modified base 4, because the significance of the i'th digit is 4^i, not 5^i.
Edited to add: I'm also not sure whether real-life implementations have -0 as an option. Of course -0 could be normalized to +0, but it might be cheaper not to bother if the sign is applied after the digit selection.