I am confused, for the dimension of A and B, the product */3000 4000 2000
should exceed the threshold and BLAS is used so that 0 T. should have no
effect on it.
can you check what is the result of  (9!:58)"0 i. 3
and also set  _1(9!:58)"0 i.3  to disable BLAS before testing

If the J binaries is compiled with OPENMP, the execution time of BLAS will
be about the same as that using 0 T.
otherwise using 0 T. instead of BLAS should be faster.



On Sun, May 22, 2022 at 5:28 AM Jan-Pieter Jacobs <
janpieter.jac...@gmail.com> wrote:

> That's very cool!
>
> A =: 3000 4000?.@$0
>
> B =: 4000 2000?.@$0
>
> 10 timespacex 'C =: A +/ .* B'
>
> 4.15287 6.71109e7
>
> 0&T.@''^:4 ''
>
> 4
>
> 10 timespacex 'C =: A +/ .* B'
>
> 2.30104 6.71109e7
>
> JVERSION
>
> Engine: j904/j64avx/linux
>
> Beta-d: commercial/2022-05-19T20:41:10
>
> Library: 9.04.01
>
> Qt IDE: 2.0.3/5.12.8(5.15.2)
>
> Platform: Linux 64
>
> Installer: J904 install
>
> InstallPath: /home/jpjacobs/j904
>
> Contact: www.jsoftware.com
>
>
> However, in J903, on the same machine, I get:
>
> A =: 3000 4000?.@$0
>
> B =: 4000 2000?.@$0
>
> 10 timespacex 'C =: A +/ .* B'
>
> 2.70296 6.71108e7
>
> JVERSION
>
> Engine: j903/j64avx/linux
>
> Release-b: commercial/2022-01-28T04:10:34
>
> Library: 9.03.08
>
> Qt IDE: 1.9.5/5.12.8(5.15.2)
>
> Platform: Linux 64
>
> Installer: J903 install
>
> InstallPath: /home/jpjacobs/j903
>
> Contact: www.jsoftware.com
>
>
> Am I right to conclude that single threaded matrix multiplication actually
> got considerably slower with respect to J903 (from 2.70 s to 4.15 s) ?
>
>
> Jan-Pieter
>
> Op vr 20 mei 2022 om 21:15 schreef Henry Rich <henryhr...@gmail.com>:
>
> > If you create threads, beta-d can use them to speed up primitives.  The
> > first primitive to get this treatment is +/ . * (designed & coded by
> Elijah
> > Stone).
> >
> > Say your machine has N cores.  Set your startup script to execute
> >
> > 0 T. ''
> >
> > N-1 times, and your matrix products will be faster with no other action
> > needed.
> >
> > Henry Rich
> >
> > On Fri, May 20, 2022, 11:07 AM Eric Iverson <eric.b.iver...@gmail.com>
> > wrote:
> >
> > > J904-beta-d is available for windows/linux/macos.
> > >
> > > If you already run J904-beta, then upgrade is easy:
> > >    load'pacman'
> > >    'upgrade'jpkg'jengine'
> > >
> > > If you have not yet installed J904-beta, time to get started!
> > >    https://code.jsoftware.com/wiki/System/Installation/J904
> > > <https://code.jsoftware.com/wiki/System/Installation/J903>
> > >
> > > Release notes:
> > >    https://code.jsoftware.com/wiki/System/ReleaseNotes/J904
> > > <https://code.jsoftware.com/wiki/System/ReleaseNotes/J903>
> > >
> > > Questions/bug reports/etc. should go to the beta forum.
> > > ----------------------------------------------------------------------
> > > For information about J forums see http://www.jsoftware.com/forums.htm
> > >
> > ----------------------------------------------------------------------
> > For information about J forums see http://www.jsoftware.com/forums.htm
> >
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
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