With pleasure. Here are two examples. The first is from my work (image
analysis). It computes the good old Haralick texture on a 5000x5000 aerial
image. The adverb Filter uses ;. to activate TextSub at every 25th pixel (1M
times).
~$ ~/j701/bin/jconsole
load '/home/ben/j701-user/temp/pgm.ijs'
CM =. 4 : '((# /.)~ y) (<"1 ~.y) } (x,x)$0'"0 2
Norm =: 3 : 'y%+/,y'
Contrast=: 3 : '+/, y * *:(<:#y)%~-/~i.#y'"2
Con =: 3 : 'Contrast Norm (+|:) y'"2 NB. for non-normalized
non-symmetrical cm
TextSub =: 4 : 0 NB. texture in a sub-image
co =. |:,.(_1&}."1 ,: 1&}."1) y
cm =. x CM co
Con cm
)
im =: <.(%16) * pgmread '/home/ben/data/Danbi/redsub.pgm'
NB. Filter applies 12&F to 7x7 subimages of <.im%16, at every 5th line and
column.
6!:2 'conperpix =. <.1000*12 TextSub Filter (5 5,:7 7) <.im%16'
87.5534
~$ wine /media/Windows/Documents\ and\ Settings/bgorte/j701/bin/jconsole.exe
....
6!:2 'conperpix =. <.1000*12 TextSub Filter (5 5,:7 7) <.im%16'
67.088
It's a 30% speed difference.
Here's a more drastic example. I guess it spends most of its time doing
extended precision things. The Fibo routine is activated recursively just 20
times or so. The result has over 200000 digits.
~$ ~/j701/bin/jconsole
Fibo =: 3 : 0"0 NB. Compute large Fibonacci numbers like Fibo 1000000
if. y<5 do. NB. returns (F y-1),F y
((,~<:)y){0 1 1 2 3x
elseif. 0=2|y do.
'b c'=.Fibo -:y
a=.c-b
d=.c+b
p=.b*a+c
q=.c*b+d
(q-p),q
elseif. do.
'b c'=.Fibo -:>:y
a=.c-b
d=.c+b
p=.b*a+c
q=.c*b+d
p,q-p
end.
)
6!:2 'z=.{:Fibo 1000000'
41.3298
~$ wine /media/Windows/Documents\ and\ Settings/bgorte/j701/bin/jconsole.exe
....
6!:2 'z=.{:Fibo 1000000'
15.5417
#":z NB.
208988
________________________________________
From: programming-boun...@forums.jsoftware.com
[programming-boun...@forums.jsoftware.com] on behalf of Michael Dykman
[mdyk...@gmail.com]
Sent: Tuesday, January 14, 2014 17:02
To: J Programming
Subject: Re: [Jprogramming] On benchmarking results from J programming styles
As the timings that you are reporting are very tiny values, we should
pause for a moment and consider a basic difference between those OSs.
Under windows, the finest-grained application timer available tick
18/s; on linux that number is 1024/s. I suggest that you try some
longer-running verbs if you expect a fair comparison.
On Tue, Jan 14, 2014 at 6:11 AM, Ben Gorte - CITG
<b.g.h.go...@tudelft.nl> wrote:
> Speaking about J, performance and Linux, is it true that Windows is
> significantly faster? Or is there something wrong with my installation? Also
> when runnning windows J under wine on my linux PC I get a better performance
> than with native linux J:
>
> NB. Native Linux
> JVERSION
> Engine: j701/2011-01-10/11:25
> Library: 7.01.087
> Platform: Linux 32
> Installer: j701a_linux32.sh
> InstallPath: /home/ben/j701
> time'locs=:nudge"1 locs'
> 1.43086e_5
> time'locs=:pfn"1 locs'
> 7.41384e_6
> time'locs=:(pfn f.)"1 locs'
> 3.77003e_6
> time'locs=:pfns"1 locs'
> 3.7135e_5
>
> NB. wine + Windows J
> JVERSION
> Engine: j701/2011-01-10/11:25
> Library: 7.01.040
> Platform: Win 32
> Installer: j701a_win.exe
> InstallPath: z:/media/windows/documents and settings/bgorte/j701
> time'locs=:nudge"1 locs'
> 1.09025e_5
> time'locs=:pfn"1 locs'
> 5.56416e_6
> time'locs=:(pfn f.)"1 locs'
> 2.88706e_6
> time'locs=:pfns"1 locs'
> 2.77585e_5
>
> Regards,
> Ben
> ________________________________________
> From: programming-boun...@forums.jsoftware.com
> [programming-boun...@forums.jsoftware.com] on behalf of Raul Miller
> [rauldmil...@gmail.com]
> Sent: Monday, January 13, 2014 06:44
> To: Programming forum
> Subject: Re: [Jprogramming] On benchmarking results from J programming styles
>
> That sounds about right.
>
> The big caution I would place on interpreting these results is: "This
> won't necessarily apply for games implemented in J for Linux, where I
> intend to rely on the SDL and byte-per-pixel graphics layouts.
> Nonetheless, I retain the logic here, since it's representative of a
> real-world design decision which directly influences performance on
> the slower Kestrel architecture."
>
> If J is to perform well when applied in suboptimal fashion we'll need
> some way of representing the code which strips out a lot of the
> functionality (type checks, size checks, rank handling, maybe even
> overflow handling?), at least for the time-critical routines. (As much
> as possible, hoisting redundant operations out of primitives used in
> bottleneck loops.)
>
> Thanks,
>
> --
> Raul
>
>
> On Sun, Jan 12, 2014 at 11:59 PM, William Tanksley, Jr
> <wtanksle...@gmail.com> wrote:
>> A friend of mine wrote the following paper describing his attempt to
>> characterize the differences between a few different styles of
>> implementing the same code in J a few different ways -- explicit,
>> implicit, and a few variations. He also baselined against a Forth
>> implementation.
>>
>> I found his writeup very interesting. What do you think?
>>
>> http://sam-falvo.github.io/2014/01/05/subroutine-performance-in-j/
>>
>> -Wm
>> ----------------------------------------------------------------------
>> 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
--
- michael dykman
- mdyk...@gmail.com
May the Source be with you.
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
