stirling-fact ( n -- fact )

Vocabulary

math.analysis

Inputs

n	an integer

Outputs

fact	an integer

Word description

James Stirling's factorial approximation.

Definition

USING: kernel math math.constants math.functions ;

IN: math.analysis

: stirling-fact ( n -- fact )
    [ pi 2 * * sqrt ] [ [ e / ] keep ^ ] [ 12 * recip 1 + ] tri
    * * ;