====== Function RANDOM ====== ====Syntax==== * **random** //limit ''&optional'' random-state// → //random-number// ====Arguments and Values==== * //limit// - a positive //[[CL:Glossary:integer]]//, or a positive //[[CL:Glossary:float]]//. * //random-state// - a //[[CL:Glossary:random state]]//. The default is the //[[CL:Glossary:current random state]]//. * //random-number// - a non-negative //[[CL:Glossary:number]]// less than //limit// and of the same //[[CL:Glossary:type]]// as //limit//. ====Description==== Returns a pseudo-random number that is a non-negative //[[CL:Glossary:number]]// less than //limit// and of the same //[[CL:Glossary: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 //[[CL:Glossary:integer]]//, each of the possible results occurs with (approximate) probability ''1<nowiki>/</nowiki>//limit//''. ====Examples==== <blockquote> ([[CL:Functions:math-not-greater|<=]] 0 (random 1000) 1000) <r>//[[CL:Glossary:true]]// </r> ([[CL:Special Operators:let]] ((state1 ([[CL:Functions:make-random-state]])) (state2 ([[CL:Functions:make-random-state]]))) ([[CL:Functions:math-equal|=]] (random 1000 state1) (random 1000 state2))) <r>//[[CL:Glossary:true]]//</r> </blockquote> ====Side Effects==== The //random-state// is modified. ====Affected By==== None. ====Exceptional Situations==== Should signal an error of type type-error if //limit// is not a positive //[[CL:Glossary:integer]]// or a positive //[[CL:Glossary:real]]//. ====See Also==== * **[[CL:Functions:make-random-state|Function MAKE-RANDOM-STATE]]** * **[[CL:Variables:star-random-state-star|Variable *RANDOM-STATE*]]** ====Notes==== See //Common Lisp the Language// for information about generating random numbers.