function powi(atom b, integer i)
atom v=1
    b = iff(i<0 ? 1/b : b)
    i = abs(i)
    while i>0 do
        if and_bits(i,1) then v *= b end if
        b *= b
        i = floor(i/2)
    end while
    return v
end function
?powi(-3,-5)
?power(-3,-5)