(gamma) ( x -- value )

Vocabulary

picomath.private

Inputs

x

an object

Outputs

value

an object

Definition

USING: kernel math math.functions sequences ;

IN: picomath.private

:: (gamma) ( x -- value )
    x :> y! 0 :> n! y 1.0 <
    :> arg-was-less-than-one arg-was-less-than-one
    [ y 1.0 + y! ] [ y floor >integer 1 - n! y n - y! ] if
    0.0 :> num! 1.0 :> den! y 1 - :> z! 8 <iota>
    [ [ P nth num + z * num! ] [ Q nth den z * + den! ] bi ]
    each num den / 1.0 + arg-was-less-than-one
    [ y 1.0 - / ] [ n [ y * y 1.0 + y! ] times ] if ;