On 2014-10-10 11:07:52 +0200, Jakub Jelinek wrote: > Though, is such optimization desirable even for fast-math?
I wonder whether fast-math has a well-defined spec, but it should be noted that because of possible cancellations, even if the final result is a float, it may be better to keep intermediate results in double if the user has used double types (explicitly or implicitly via a function that returns a double). For instance, if x is a double, (float) sin(x) and (float) sin((float) x) can give very different results if x is large compared to the period (2*pi). -- Vincent Lefèvre <vinc...@vinc17.net> - Web: <https://www.vinc17.net/> 100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/> Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
