Is it possible to roll a significantly faster version of sqrt

Question

In an app I\'m profiling, I found that in some scenarios this function is able to take over 10% of total execution time.

I\'ve seen discussion over the years of fast

Answer 1

How accurate do you need your sqrt to be? You can get reasonable approximations very quickly: see Quake3's excellent inverse square root function for inspiration (note that the code is GPL'ed, so you may not want to integrate it directly).