Le 22/01/2020 à 15:41, Dima Pasechnik a écrit :
On Wed, Jan 22, 2020 at 2:31 PM Vincent Delecroix
<[email protected]> wrote:
I had the same annoying trouble... Is it really a bug in arch? I don't
find anywhere where libopenblas is supposed to provide the LAPACK
interface. To me it is just true for SageMath and false for Archlinux.
well, a "bug", in the sense that their openblas configuration just
does not make any sense,
because if you install a highly optimised BLAS implementation, which can also
provided a highly optimised CBLAS and LAPACK, in a sane world you'd install them
too. But Arch does not do this, it instead provides dog-slow CBLAS and
LAPACK, built
from another (reference, i.e. no assembler, no optimisation) implementation.
This causes Sage's logic, which expects that openblas will also
provide CBLAS and LAPACK, to fail.
Yes, it is possible to make tests to detect this silly setup, but I
think that everyone's time
is much better spent if Arch provided a full build of openblas, with
CBLAS and LAPACK,
instead.
Hence there are two bugs
* a "logical" bug in archlinux that provides a slow lapack for
(apparently) no good reason
* a structural bug in SageMath that assumes that openblas does
install the LAPACK interface
I tend to agree that the resolution of any of these two would solve
the compilation. But in an ideal world we would just solve the two.
Le 13/01/2020 à 11:44, Dima Pasechnik a écrit :
On Sat, Jan 11, 2020 at 11:35 AM arojas <[email protected]> wrote:
El sábado, 11 de enero de 2020, 11:23:32 (UTC+1), Dima Pasechnik escribió:
On Sat, 11 Jan 2020, 10:19 arojas, <[email protected]> wrote:
I suspect this may be due to our openblas package only providing libblas.so
(not libcblas.so or liblapack.so, which in our case come from the netlib blas).
Are you saying that your libopenblas.so does not provide everything that is in
openblas by default?
This is largely defeating its purpose.
Sage's openblas does provide the cblas and lapack capabilities.
In that case, openblas' spkg-configure should check whether cblas symbols
are provided by the system openblas, and if not it should compile sage's one.
It shouldn't unconditionally assume that that's always the case.
I maintain that it's a bug in Arch, that libopenblas cannot be used as
a replacement of cblas and lapack, for it defeats its purpose.
Most uses of BLAS routines are either via LAPACK, or from C/C++, via cblas.
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