gammaln ( x -- gamma[x] )

Vocabulary

math.analysis

Inputs

x

a number

Outputs

gamma[x]

a number

Word description

An alternative to gamma when gamma(x)'s range varies too widely.

Definition

USING: kernel math math.analysis.private ;

IN: math.analysis

: gammaln ( x -- gamma[x] )
    dup 0 <
    [ drop 1/0. ] [
        [ abs gammaln-lanczos6 ] keep dup 0 >
        [ drop ] [ gamma-neg ] if
    ] if ;