The Art of Mathematics

Help 6.41

sign — signum function

1. Definition

Signum function is defined as

sign(x) ≡ −1, for x < 0;
sign(0) ≡ 0;
sign(x) ≡ 1, for x > 0.

2. Graph

Signum function is defined everywhere on real axis — so its domain is (−∞, +∞). Function graph is depicted below — fig. 1.

Fig. 1. Graph y = sign x. Fig. 1. Graph of the signum function y = signx.

Function codomain is limited to the set of values {−1, 0, 1}.

3. How to use

To get signum of the number:

sign(−1.7);

To get signum of the complex number:

sign(−1.7+i);

To get signum of the current result:

sign(rslt);

To get signum of the number z in calculator memory:

sign(mem[z]);

5. Support

Signum of the real argument is supported in free version of the Librow calculator.

Signum of the complex argument is supported in professional version of the Librow calculator.