frexp ( x -- y exp )

Vocabulary

math.functions

Inputs

x

a number

Outputs

y	a float
exp	an integer

Word description

Break the number x into a normalized fraction y and an integral power of 2 e^.

The function returns a number y in the interval [1/2, 1) or 0, and a number exp such that x = y*(2**exp).

Definition

IN: math.functions

GENERIC: frexp ( x -- y exp )

Methods

USING: kernel math math.functions ;

M: float frexp
    dup fp-special? [ dup zero? ] unless*
    [ 0 ] [
        double>bits [
            9227875636482146303 bitand 0.5 double>bits bitor
            bits>double
        ] [ -52 shift 2047 bitand 1022 - ] bi
    ] if ; inline


USING: kernel math math.functions ;

M: integer frexp
    [ 0.0 0 ] [
        dup 0 > [ 1 ] [ abs -1 ] if swap dup log2 [
            52 swap - shift 4503599627370495 bitand
            0.5 double>bits bitor bits>double
        ] [ 1 + ] bi [ * ] dip
    ] if-zero ; inline