^ operation much slower in R 1.7.1 than in R 1.7 .0 ???

-----Original Message-----
From: Prof Brian Ripley [mailto:ripley@stats.ox.ac.uk]
Sent: 05 August 2003 09:50
To: Marsland, John
Cc: r-devel@stat.math.ethz.ch
Subject: RE: [Rd] RE: [R] ^ operation much slower in R 1.7.1 than in R
1.7 .0 ???


So that pretty conclusively nails this as a compiler/runtime 
difference.
Which versions of the compiler and mingw-runtime did you use?

We'll need to wait until Duncan M returns to find out what he used.

On Tue, 5 Aug 2003, Marsland, John wrote:

I have both the CRAN binary and my own compiled version of 

R v1.7.1 on the

same machine (Dell Pentium III 800 MHz running NT 4)

Using the example provided earlier:

phi <- 1.6180339887498949
a <- floor(runif(750000)*1000)
system.time(b <- (phi^a - (-phi)^(-a))/sqrt(5))[3]

I get 10.99 secs on the CRAN binary and 2.09 secs on my own compiled
version.

I hope this helps someone ... 

Regards,

John Marsland

-----Original Message-----
From: Prof Brian D Ripley [mailto:ripley@stats.ox.ac.uk]
Sent: 05 August 2003 09:03
To: Philippe Grosjean
Cc: r-devel@stat.math.ethz.ch
Subject: [Rd] RE: [R] ^ operation much slower in R 1.7.1 than 
in R 1.7.0
???


On Tue, 5 Aug 2003, Philippe Grosjean wrote:

I propose to move this thread to R-devel...

Prof. Brian Ripley wrote:

And are you able to give an explanation?  For example, did 

you compile

each under the same compiler system?

I just noticed that behaviour yesterday, and had not much 

time yet to

investigate it. I compiled 1.7.0 myself (but compared with 

the binary

provided on CRAN; no changes). I used the 1.7.1 binary 

provided on CRAN. I

know these binaries are not supported, so we (Windows 

users) will have to

look at that by ourselve. Indeed yes, I'll first compile 

1.7.1 with the same

compiler I used for 1.7.0.

I doubt if this is worth R-core's time to pursue, so over 

to interested

users to find an explanation and fix.

OK. But I was wondering if people at R-core team, 

especially those who

worked on Windows specific aspects, would have in mind some 

changes they did

between 1.7.0 and 1.7.1 than can cause this. Since these 

changes are mainly

corrections of bugs, the list is hopefully not so long... 

and it could help

a lot to have these hints. Thanks very much.

No idea from me, and the effect is not seen on other platforms.

-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  

University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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