# A word to describe the act to switch between positive and negative?

I am doing some programming with math. I have written a tidy function which turns any positive number to negative or any negative number to a positive.

I would like to name this function in the most informative way so that if someone else were to look at my function; they would understand, straight away, what it does (and expect what it says on the tin).

The best word I can come up with is 'flip' but I feel that it fails at being obvious.

The function belongs to the Math object so it looks like this:

``````answer = Math.flip(number)
``````

The results might be

``````-1 = Math.flip(1)
``````

or

``````1 = Math.flip(-1)
``````

How can I best describe this act?

• My calculator uses CHS ( change sign).
– Jim
Jun 25, 2015 at 23:52
• Most if not all programming languages don't have a name for this function because it is achieved by simple use of the minus sign: 1 = - (-1). I hope you aren't really having to write a function that does that.
– Avon
Jun 26, 2015 at 0:00
• What @Avon said. But if you really wanted to implement such a function, negate would surely be a natural name for it. negate(-1) returns +1, obviously. Jun 26, 2015 at 0:01
• @FumbleFingers negate's good but it has, sort of 'nullify' connotations to me. How about minus(1)?
– Avon
Jun 26, 2015 at 0:03
• Interestingly, x *= -1; is regarded on stackoverflow as the best way to do it in Java (stackoverflow.com/questions/7869911/…). Horrifyingly, x = x * -1 is regarded as the best way in C# (stackoverflow.com/questions/1348080/…) and x = System.Math.Abs(x) * (-1); comes in second. I think people might have been poking fun there.
– Avon
Jun 26, 2015 at 0:17

invert

verb
1.3 chiefly Mathematics Subject to inversion; transform into its inverse.

(oxforddictionaries.com)

but it has lots of meanings in maths. More precisely, it is the Additive Inverse

the additive inverse of a number a is the number that, when added to a, yields zero

and not to be confused with Multiplicative Inverse

a multiplicative inverse or reciprocal for a number x, denoted by 1/x or x−1, is a number which when multiplied by x yields the multiplicative identity, 1

(wikipedia)

So... err... invert additively? It's not very good, sorry.

• invert is good! Jun 26, 2015 at 13:10