Hello,
I'm working in a quite complex algorithm. I try to improve the performance using iFort. With gfortran I obtain same numeric results if I use -O0, -O1, -O2 or O3 optimization flags. With a old version (2013?) of iFort and only could reproduce this values if I use -O0. With newer version (2014 and 2015) I can reproduce the values using -O0 or -O1 but if I try to use -O2 or -O3 I can't. I understand that -O2 should has same results but quicker (I fact is much quicker but different results). When I say that results are different I say they are "little bit" different but it is important to know why. Could you give some ideas or advices about how to proceed? I should forget use ifort or there is tools for understand what is going on and improve it. Also, I think that could be a compiler bug because with older version I can't obtain same results with -O1 (only with -O0) and with new version I can. Without change the code.
Anyway, I have to say that ifort with -O1 is already faster than gfortran.
Thanks
