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Diffstat (limited to 'random.txi')
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diff --git a/random.txi b/random.txi new file mode 100644 index 0000000..f144837 --- /dev/null +++ b/random.txi @@ -0,0 +1,69 @@ + + + + + +@defun random n + + +@defunx random n state +Accepts a positive integer or real @var{n} and returns a number of the +same type between zero (inclusive) and @var{n} (exclusive). The values +returned by @code{random} are uniformly distributed from 0 to @var{n}. + +The optional argument @var{state} must be of the type returned by +@code{(seed->random-state)} or @code{(make-random-state)}. It defaults +to the value of the variable @code{*random-state*}. This object is used +to maintain the state of the pseudo-random-number generator and is +altered as a side effect of calls to @code{random}. +@end defun + + + + +@defvar *random-state* +Holds a data structure that encodes the internal state of the +random-number generator that @code{random} uses by default. The nature +of this data structure is implementation-dependent. It may be printed +out and successfully read back in, but may or may not function correctly +as a random-number state object in another implementation. +@end defvar + + +@defun copy-random-state state + +Returns a new copy of argument @var{state}. + + +@defunx copy-random-state +Returns a new copy of @code{*random-state*}. +@end defun + + + +@defun seed->random-state seed + +Returns a new object of type suitable for use as the value of the +variable @code{*random-state*} or as a second argument to @code{random}. +The number or string @var{seed} is used to initialize the state. If +@code{seed->random-state} is called twice with arguments which are +@code{equal?}, then the returned data structures will be @code{equal?}. +Calling @code{seed->random-state} with unequal arguments will nearly +always return unequal states. +@end defun + + + +@defun make-random-state + + +@defunx make-random-state obj +Returns a new object of type suitable for use as the value of the +variable @code{*random-state*} or as a second argument to @code{random}. +If the optional argument @var{obj} is given, it should be a printable +Scheme object; the first 50 characters of its printed representation +will be used as the seed. Otherwise the value of @code{*random-state*} +is used as the seed. +@end defun + + |