signum is:exact

Sign of a number. The functions abs and signum should satisfy the law:

abs x * signum x == x

For real numbers, the signum is either -1 (negative), 0 (zero) or 1 (positive).

Scale a complex number to magnitude 1. For a complex number z, abs z is a number with the magnitude of z, but oriented in the positive real direction, whereas signum z has the phase of z, but unit magnitude.

Determine the 'sign' of a value.

The sign of a number.

>>> signum (-1)
-1

abs zero == zero, so any value for signum zero is ok. We choose lawful neutral:

>>> signum zero == zero
True

Takes the sign of a Quantity. The functions abs and signum satisy the law that:

abs x * signum x == x

The sign is either negate _1 (negative), _0 (zero), or _1 (positive).