HELP RANDOM_STATES John Williams, Oct 1986
The library package LIB * RANDOM_STATES creates a record class called
"random_state". Such objects encapsulate the state of a pseudo random
number generator. When applied to a number N, a random_state returns a
random number M where M >= 0 and M <= N. Random_states can be copied;
the original and the copy produce identical series of numbers if applied
to the same arguments.
Objects of the POP11 class "random_state" are identical to objects of
the Common Lisp type RANDOM-STATE.
The following functions operate on random_states:
consrandom_state(<integer | false:I>) -> <random_state>
Constructs a random_state object, with 'seed' value initialised
to I. If I is -false-, the seed is given some randomly chosen
value
destrandom_state(<random_state>) -> <integer | false>
Stacks the components of <random_state>, i.e. the 'seed' value
israndom_state(<item>) -> <boolean>
-true- if <item> is a random_state, -false- otherwise
random_seed(<random_state>) -> <integer | false>
<integer | false> -> random_seed(<random_state>)
Returns/updates the 'seed' of the given <random_state>
apply_random_state(<integer | float:N>, <random_state>)
-> <integer | float:M>)
Returns a random number M where M >= 0 and M <= N
This procedure is the -class-apply- of random_state objects
The key of random_state objects is held in the constant 'random_state_key'
-- Example -------------------------------------------------------------
vars r = consrandom_state(false);
r =>
** <random_state <false>>
repeat 3 times r(100) => endrepeat;
** 47
** 50
** 82
define nextfrom(n, state);
copy(state)(n)
enddefine;
nextfrom(100, r) =>
** 86
r(100) =>
** 86
-- See also ------------------------------------------------------------
HELP * RANDOM
REF * NUMBERS
-----<Copyright University of Sussex 1986. All rights reserved.>-------