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
