Floating point calculation differences with AVX instructions

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi

We have observed that the results of some floating point calculations
change when compiler flag:

-march=native

is used. This can happen even for relatively simple expressions such as:

x*x+y*y

where x and y are double precision. The observed difference is in the least
significant bit of the mantissa, which suggests a rounding issue. Is this
expected behaviour?

Is it because the FPU uses 80-bit extended precision for intermediate
results whereas the AVX hardware does not?

Best regards

David



[Index of Archives]     [Linux C Programming]     [Linux Kernel]     [eCos]     [Fedora Development]     [Fedora Announce]     [Autoconf]     [The DWARVES Debugging Tools]     [Yosemite Campsites]     [Yosemite News]     [Linux GCC]

  Powered by Linux