Simplified Common Lisp reference
Symbol class: Mathematics, Arithmetics, Logic and Comparisons
Symbol type: function
randomlimitrandom-state(optional) => numeric value
Argument description:
limit positive number, integer or real
random-state object representing random state

RANDOM function generates random numbers. For integer argument N, result is integer between zero (including) and N (excluding). For real argument X, result is real between zero (including) and X (excluding). All generated numbers have approximately same probability. Default value for random-state is stored in *random-state* global variable.

(<= 0 (random 20) 19) => T
(let ((x (random 1.0))) (or (= x 0) (< 0 x 1.0))) => T
Function indexFull documentation for random (HyperSpec)