[Wien] Compiling Wien2k 21.1 on Ubuntu 20.04 with gfortran

[Pavel Ondračka]

On Wed, 2021-11-24 at 16:51 +0100, Peter Blaha wrote:
> Just for information:  the -DHAVE_LIBMVEC is a preprocessor option
> (like -DINTEL_VML for ifort) and will speedup the HAMILT part due to
> a vectorization of cosine/sine functions.

Sorry for not being specific enough, -DHAVE_LIBMVEC should go to the
Wien2k compiler options, specifically add it to the "-ffree-form -O2 -
ftree-vectorize -march=native -ffree-line-length-none -ffpe-
summary=none" stuff

If you add it together with the -Dparallel (as I now see in the other
email), it will be available only for the mpi builds.

> As far as I remember, it is available only with more recent
> gfortran/openblas versions, therefore not yet a "default" gfortran
> option.

This is actually a Glibc feature (alternative to intel VML), introduced
with glibc 2.22 released in mid 2015. It is not on by default because 
at the time I wrote that stuff not all distros had it. Nowadays the are
still enterprise distros like old RHEL, CENTOS, or similar that use
older glibc (however this is mostly HPC where one would compile with
ifort anyway). All supported desktop distros like Fedora, Ubuntu,
Opensuse, etc. have is now, so it should be safe to add to
gfortran/openblas flags by default in the next release. 

Best regards
Pavel

> ----------------------------
> Hi Pavel,
> 
> I don't think that that compiler flag has been used:
>  $ find . -name "Makefile" -exec grep "DHAVE_LIBMVEC" {} \;
> yields nothing in my Wien2k source directory.
> 
> David
> 
> Am 24.11.2021 um 14:43 schrieb Pavel Ondračka:
>  
> > Dear David,
> > 
> > nice, ~30 seconds instead of ~150 :-)
> > BTW is this already with "-DHAVE_LIBMVEC" in compiler options?
> > 
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at: 
> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html