idempotent
Jan. 19th, 2016 07:56 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
prettygoodwordidempotent (AY-duhm-poht-nt, ID-uhm-poht-nt) - n., (math, comp. sci.) (of operators and functions) can be applied multiple times without any change after the first application; (of an algebraic quantity) can be multiplied by itself without changing its value.
So in ordinary arithmetic, 1 is idempotent in the second sense: 1 × 1 = 1. As a function, absolute value is idempotent -- abs(abs(x)) = abs(x) -- as is Boolean "and" -- x & x = x. Contrast with nullipotent, meaning doing it multiple times is the same as doing it zero times. Coined in 1870 by American mathematician Benjamin Peirce from Latin roots idem, same + potent, having power -- "having the same power."
---L.
So in ordinary arithmetic, 1 is idempotent in the second sense: 1 × 1 = 1. As a function, absolute value is idempotent -- abs(abs(x)) = abs(x) -- as is Boolean "and" -- x & x = x. Contrast with nullipotent, meaning doing it multiple times is the same as doing it zero times. Coined in 1870 by American mathematician Benjamin Peirce from Latin roots idem, same + potent, having power -- "having the same power."
---L.
