/**

* @function signum

* @description Returns the sign of a number

* @summary The signum function is an odd mathematical function, which returns the

* sign of the provided real number.

* It can return 3 values: 1 for values greater than zero, 0 for zero itself,

* and -1 for values less than zero

* @param {Number} input

* @returns {-1 | 0 | 1 | NaN} sign of input (and NaN if the input is not a number)

* @see [Wikipedia](https://en.wikipedia.org/wiki/Sign_function)

* @example signum(10) = 1

* @example signum(0) = 0

* @example signum(-69) = -1

* @example signum("hello world") = NaN

*/

export const signum = (num: number) => {

if (num === 0) return 0

if (num > 0) return 1

if (num < 0) return -1

return NaN

}