kth-object-impl ( seq k nth-quot exchange-quot quot: ( x y -- ? ) -- elt )

Vocabulary

math.statistics.private

Inputs

seq	an object
k	an object
nth-quot	an object
exchange-quot	an object
quot	a quotation with stack effect ( x y -- ? )

Outputs

elt

an object

Definition

USING: kernel math sequences sequences.private ;

IN: math.statistics.private

:: kth-object-impl
    ( seq k nth-quot exchange-quot quot: ( x y -- ? ) -- elt )
    k seq bounds-check 2drop
    0 :> i! 0 :> j! 0 :> l! 0 :> x! seq length 1 - :> m!
    [ l m < ] [
        k seq nth-unsafe x! l i! m j!
        [ i j <= ] [
            [ i seq nth-quot call x quot call ] [ i 1 + i! ]
            while
            [ x j seq nth-quot call quot call ] [ j 1 - j! ]
            while i j <=
            [ i j seq exchange-quot call i 1 + i! j 1 - j! ]
            when
        ] do while j k < [ i l! ] when k i < [ j m! ] when
    ] while k seq nth-unsafe ; inline