I tested with J calling lapack for matrix multiplication with the
following script,
NB. extern dgemm_(char * transa, char * transb, int * m, int * n, int * k,
NB. double * alpha, double * A, int * lda,
NB. double * B, int * ldb, double * beta,
NB. double * C, int * ldc);
dgemm=: 'liblapack.so.3 dgemm_ > n *c *c *i *i *i *d *d *i *d *i *d *d *i'&cd
mm=: 4 : 0
k=. ,{.$x
c=. (k,k)$1.5-1.5
dgemm (,'T');(,'T');k;k;k;(,2.5-1.5);x;k;y;k;(,1.5-1.5);c;k
c
)
'A B'=:0?@$~2,,~4096
echo timespacex'A+/ .*B'
echo timespacex'A mm B'
result was,
19.3608 2.68437e8
0.886447 2.68442e8
Note it need to use an optimized version of blas, not the
reference blas.
Apparently the blas used in julia is sub-optimal.
Вт, 18 апр 2017, bill lam написал(а):
> I think julia just calls blas.
>
> Пн, 17 апр 2017, Xiao-Yong Jin написал(а):
> >
> > > On Apr 17, 2017, at 9:26 PM, Henry Rich <[email protected]> wrote:
> > >
> > > If you have an implementation of +/ . * on double-precision floats that's
> > > faster than J 8.06, I would be obliged if you'd send me a copy of the
> > > source code.
> >
> > I'm sure your code is much faster than naive c loops. But some how the
> > matrix-matrix multiplication is much slower (10x) than that in julia
> > (tested with a 3-year old version).
> >
> > % julia
> > _
> > _ _ _(_)_ | A fresh approach to technical computing
> > (_) | (_) (_) | Documentation: http://docs.julialang.org
> > _ _ _| |_ __ _ | Type "help()" to list help topics
> > | | | | | | |/ _` | |
> > | | |_| | | | (_| | | Version 0.2.1 (2014-02-11 06:30 UTC)
> > _/ |\__'_|_|_|\__'_| |
> > |__/ | x86_64-linux-gnu
> >
> > julia> A=rand(4096,4096); B=rand(4096,4096);
> >
> > julia> @time A*B;
> > elapsed time: 2.260157127 seconds (149184640 bytes allocated)
> >
> > julia>
> > % jconsole
> > JVERSION
> > Engine: j806/j64avx/linux
> > Beta-3: commercial/2017-04-10T17:51:14
> > Library: 8.06.02
> > Platform: Linux 64
> > Installer: J806 install
> > InstallPath: /nfs2/xjin/pkgs/j64-806
> > Contact: www.jsoftware.com
> > 'A B'=:0?@$~2,,~4096
> > timespacex'A+/ .*B'
> > 23.8976 2.68437e8
> > timespacex'A+/ .*B'
> >
> > ----------------------------------------------------------------------
> > For information about J forums see http://www.jsoftware.com/forums.htm
>
> --
> regards,
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