Re:Revisiting the Fast Inverse Square Root – Is It Still Use...
by stephencanon on Friday April 21, 2023 @07:43PM
(#35661725)
Division is actually pretty straightforward: compute a residual using the multiply-add that you already have, divide _that_, and then add it to the quotient.
Or (roughly equivalently, but maybe easier to understand) do a native double division, then do a Newton-Raphson step, which requires only multiplication and addition (just like you would refine a reciprocal estimate).
Or (roughly equivalently, but maybe easier to understand) do a native double division, then do a Newton-Raphson step, which requires only multiplication and addition (just like you would refine a reciprocal estimate).