I Can't Believe It's Not Zero!Feb 12, 2023

Proposal: people prefer “mantissa” because it abbreviates better than “significand” (any truncation of which collides with “sign”). But “mantissa” is formally incorrect, since it already has a different meaning. So we should use “magnificand” instead.

- code that uses (s,e,m) still makes sense
- it’s the thing that is magnified by the exponent—the magnificand
- magnificent

Show threadTiago PeixotoFeb 13, 2023
@steve What is the different meaning of “mantissa”?
Show threadI Can't Believe It's Not Zero!Feb 13, 2023
@tiago traditionally (pre-floating-point), “mantissa” meant the fractional part of the logarithm, used in log tables for computation. E.g. using the base-10 log of 150 as an example, the “characteristic” (integer part) is 2, and the “mantissa” (fractional part) is something like 0.1761.
Show threadI Can't Believe It's Not Zero!Feb 13, 2023
@tiago that’s closely related to, but not the same as the thing we call “significand” or “mantissa” when we talk about floating-point (in the example above, the significand would be 10^0.1761 = 1.5 if we normalized decimal FP like we do binary FP).
Show threadTiago Peixoto
@steve Understood! I've never seen this original meaning of mantissa before. It seems its usage has died out together with logarithm tables.
Feb 13, 2023 at 6:16pmWeb