3 ms·
That's a different case where one is trying to calculate rsqrt(x) from 1/sqrt(x) whereas the article involves computing sqrt(x) from x*rsqrt(x) and in this case
by dooglius 2y ago
That's a different case where one is trying to calculate rsqrt(x) from 1/sqrt(x) whereas the article involves computing sqrt(x) from x*rsqrt(x) and in this case you don't need the divps instruction for sqrt but do need an additional mul instruction for the rsqrt case.
- GrantMoyer 2y agoI think you've misread the section: > it is possible to speed up single-precision divide and square root calculations using the (V)RSQRTPS and (V)RCPPS instructions