performance - Fast sqrt in Java at the expense of accuracy

Question

I am looking for a fast square root implementation in Java for double values in the input range of [0, 2*10^12]. For any value in this range, the precision should be upto 5 decimal places. In other words, the result can differ from the Math.sqrt() method after 5 decimal places. However, this method needs to be much faster than Math.sqrt().

Any ideas? Thanks!

Answer 1

I don't believe (without a benchmark to prove this wrong) that a pure Java implementation could me much faster than Math.sqrt(). Both the Oracle JRE implementation and the OpenJDK implementation are native implementations.