ldexp ( x exp -- y )

Vocabulary

math.functions

Inputs

x	a number
exp	a number

Outputs

y

a number

Word description

Multiply x by 2^exp.

Notes

ldexp is the inverse of frexp.

Definition

IN: math.functions

GENERIC#: ldexp 1 ( x exp -- y )

Methods

USING: combinators kernel math math.functions ;

M: float ldexp
    over fp-special? [ over zero? ] unless*
    [ drop ] [
        [ double>bits dup -52 shift 2047 bitand 1023 - ] dip + {
            { [ dup -1074 < ] [ drop 0 copysign ] }
            { [ dup 1023 > ] [ drop 0 < -1/0. 1/0. ? ] }
            [
                dup -1022 < [ 52 + -52 2^ ] [ 1 ] if
                [ -9218868437227405313 bitand ]
                [ 1023 + 52 shift bitor bits>double ] [ * ] tri*
            ]
        } cond
    ] if ;


USING: kernel math math.functions ;

M: integer ldexp
    2dup [ zero? ] either? [ 2drop 0 ] [ shift ] if ;