CLCS
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Index
make-random-state Numbers Dictionary random-state-p
Function

random

random limit &optional random-state ⇒ random-number

Arguments and Values

limita positive integer, or a positive float.
random-statea random state. The default is the current random state.
random-numbera non-negative number less than limit and of the same type as limit.

Description

Returns a pseudo-random number that is a non-negative number less than limit and of the same type as limit.

The random-state, which is modified by this function, encodes the internal state maintained by the random number generator.

An approximately uniform choice distribution is used. If limit is an integer, each of the possible results occurs with (approximate) probability 1/limit.

Examples

 (<= 0 (random 1000) 1000) ⇒  true
 (let ((state1 (make-random-state))
       (state2 (make-random-state)))
   (= (random 1000 state1) (random 1000 state2))) ⇒  true

Side Effects

The random-state is modified.

Exceptional Situations

Should signal an error of type type-error if limit is not a positive integer or a positive real.

See Also

make-random-state, random-state

Notes

See Common Lisp: The Language for information about generating random numbers.

Backlinks

*random-state*, Additional Constraints on Externalizable Objects, Definition of Similarity, make-random-state, Modification of Literal Objects, Numbers Dictionary, Random-State Operations, random-state, Symbols in the COMMON-LISP Package