Hi Barry,
Thanks for the advice. It took me a while to compile and build
successfully with gfortran due to the stricter rules and entirely
different options.
But the most problematic thing was that most clusters I work with use
old versions of gcc/gfortran. With the gcc/gfortran tied to the MPI, it
seems that I can't just update myself to use the new version, or can I?
Also, can anyone recommend options to get optimized results in gfortran?
I'm using :
-fno-signed-zeros -fno-trapping-math -ffast-math -march=native
-funroll-loops -ffree-line-length-none -O3
Thank you.
Yours sincerely,
TAY wee-beng
On 8/4/2014 8:04 PM, Barry Smith wrote:
You should never get yourself in a position where you “have to” use a
particular compiler. Strive to have portable makefiles that don’t depend on the
compiler (with PETSc makefiles this is easy) and to have portable code that
doesn’t depend on the compiler. Then switching between compilers takes
literally a couple minutes. It is extremely counter productive to do nothing
for days because the compiler you are using doesn’t work under a particular
circumstance. It really isn’t hard to set things up so changing compilers is
easy.
Barry
On Apr 8, 2014, at 6:39 AM, Jed Brown <[email protected]> wrote:
TAY wee-beng <[email protected]> writes:
My impression was intel is mostly faster. However, does it apply to
gfortran too? Is it also faster for a lot of code than Intel fortran?
I'll give it a go if it's so. However, I remember changing a no. of
options to build and in the end, it was slower. that's a few yrs ago though.
It varies, but usually not by a large factor and a broken compiler takes
infinitely long to produce correct answers. Report the bug to Intel,
use gfortran (latest version), and get on with your business. If/when
Intel fixes the bug, if you still have a license, try ifort again.
