interval* ( i1 i2 -- i3 )
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Vocabulary
math.intervals

Inputs

i1	an interval
i2	an interval

Outputs

i3	an interval

Word description
Multiplies two intervals.

The output interval contains all possible values from multiplying any number in i1 with any number in i2.

Examples

USING: math.intervals prettyprint ; 10 11 [a,b] 5 7 [a,b] interval* .
T{ interval { from { 50 t } } { to { 77 t } } }

USING: math.intervals prettyprint ; -10 11 [a,b] 5 7 [a,b] interval* .
T{ interval { from { -70 t } } { to { 77 t } } }

Definition

USING: kernel math ;

IN: math.intervals

: interval* ( i1 i2 -- i3 )
    [ [ [ * ] interval-op nan-ok ] do-empty-interval ]
    [ [ interval-zero? ] either? ] 2bi
    [ 0 [a,a] interval-union ] when ;