Note 'Roger''s Post'
Roger's post led me to consider applying "_1
(the default) to +/ and I was surprised that
there could be substantial differences in relative
performance - is there more to be wrung out of
the performance of this classic computation in J?
For large scale simulations the differences are large
enough to want to consider the detail of the code
for data objects of different shape.
)
ts=: 6!:2 , 7!:[EMAIL PROTECTED]
v =: 3 : 0
d =. ts '(+/%#) y'
f =. ts '(+/"_1%#) y'
d,:f
)
x1=: 5 5e5 [EMAIL PROTECTED] 0 NB. wide
x2=: 5e5 5 [EMAIL PROTECTED] 0 NB. tall
x3=: 1580 1600 [EMAIL PROTECTED] 0 NB. squarish
v x1
0.0450473 8.38982e6
0.00966296 1792
v x2
0.0124485 1472
0.0334677 8.39014e6
v x3
0.0105466 33984
0.00992556 34304
Note''
Should we conclude the following:
In wide cases use "_1
In tall cases use without rank
In squarish cases it probably does not matter
ts is so widely used in this forum it should be
in the standard library!
)
----- Original Message -----
From: "Roger Hui" <[EMAIL PROTECTED]>
To: "Programming forum" <[email protected]>
Sent: Thursday, July 26, 2007 7:09 PM
Subject: Re: [Jprogramming] (+/%#)"r
Sorry, the mailer made a hash of my msg.
+/"r has integrated rank
support but (+/%#)"r does not.
Therein lies an opportunity for an
improvement in the
implementation.
ts=: 6!:2 , 7!:[EMAIL PROTECTED]
x=: 5 5e5
[EMAIL PROTECTED] 0 NB. wide
ts '(+/%#)"1 x'
0.0777057 4.1961e6
ts '(+/"1
x)%{:$x'
0.0110925 1792
x=: 5e5 5 [EMAIL PROTECTED] 0 NB. tall
ts
'(+/%#)"1 x'
0.612025 4.1961e6
ts '(+/"1 x)%{:$x'0.033295 8.39014e6
x=: 1580 1600 [EMAIL PROTECTED] 0 NB. squarish
ts '(+/%#)"1 x'
0.0167924 34432
ts '(+/"1 x)%{:$x'
0.0112939 34304
----- Original Message -----
From: Roger Hui <[EMAIL PROTECTED]>
Date: Thursday, July 26, 2007 0:04
Subject: [Jprogramming] (+/%#)"r
To: Programming forum <[email protected]>
+/"r has integrated rank support but (+/%#)"r does not.Therein
lies an opportunity for an improvement in the implementation.
ts=: 6!:2 , 7!:[EMAIL PROTECTED] x=: 5 5e5 [EMAIL PROTECTED] 0 NB. wide ts '(+/%#)"1
x'0.0777057 4.1961e6 ts '(+/"1 x)%{:$x'0.0110925 1792
x=: 5e5 5 [EMAIL PROTECTED] 0 NB. tall ts '(+/%#)"1 x'0.612025
4.1961e6 ts '(+/"1 x)%{:$x'0.033295 8.39014e6 x=: 1580
1600 [EMAIL PROTECTED] 0 NB. squarish ts '(+/%#)"1 x'0.0167924 34432 ts
'(+/"1 x)%{:$x'0.0112939 34304
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