(gamma-random>1) ( alpha beta rnd -- n )

Vocabulary

random.private

Inputs

alpha	an object
beta	an object
rnd	an object

Outputs

n

an object

Definition

USING: combinators.short-circuit kernel math math.functions
random ;

IN: random.private

:: (gamma-random>1) ( alpha beta rnd -- n )
    2.0 alpha * 1 - sqrt :> ainv alpha 4.0 log -
    :> bbb alpha ainv + :> ccc 0 :> r! 0 :> z! 0 :> result! [
        r
        { [ 1.0 4.5 log + + z 4.5 * - 0 >= ] [ z log >= ] } 1||
        not
    ] [
        rnd random-unit* :> u1 rnd random-unit* :> u2 u1 1.0 u1
        - / log ainv / :> v alpha v e^ * :> x u1 sq u2 *
        z! bbb ccc v * + x - r! x beta * result!
    ] do while result ;