Byte code compile not helpful in R3.0.2

My bad to not give details. I'm comparing (though not quite directly) to
results in the posting
http://rwiki.sciviews.org/doku.php?id=tips:rqcasestudy.

What prompted the query was a write up of "for" versus "while" loops,
where there was a speedup using compiler for one of these. I had the
example in a knitr file, and when I was reviewing the text before
sending it to an editor, I realized the timings no longer supported the
text. They were, as I recall, developed in R 2.15.2, and I just looked
through my VMs with different OS's to see if there is one with that
still extant, but except for a real Win7 case I have been too "good" and
updated to at least 3.0.1, where I'm getting no advantage. The Win7 case
is R 2.15.1, and there the compiler actually went slower on one run of
the code below. That may be due to antivirus running -- had not booted
that partition for quite a while.

Here is the for-while test code:

#  forwhiletime.R
library(microbenchmark)
require(compiler)

tfor <- function(n){
    for (i in 1:n) {
       xx<-exp(sin(cos(as.double(i))))
    }
    xx
}

twhile <- function(n){
    i<-0
    while (i<n) {
       i<-i+1
       xx<-exp(sin(cos(as.double(i))))
    }
    xx
}
n<-10000

timfor<-microbenchmark(tfor(n))
timwhile<-microbenchmark(twhile(n))
timfor
timwhile
cmpfun(tfor)
cmpfun(twhile)
timforc<-microbenchmark(tfor(n))
timwhilec<-microbenchmark(twhile(n))
timforc
timwhilec
looptimes<-data.frame(timfor$time, timforc$time, timwhile$time,
timwhilec$time)
colMeans(looptimes)


Actually, I'm not greatly axious about all this. Mainly I want to make
sure that I get whatever advice is to be rendered so it is correct.

Best,

JN


On 13-11-03 02:22 PM, Duncan Murdoch wrote:

On 13-11-03 2:15 PM, Prof J C Nash (U30A) wrote:

I had a bunch of examples of byte code compiles in something I was
writing. Changed to 3.0.2 and the advantage of compiler disappears. I've
looked in the NEWS file but do not see anything that suggests that the
compile is now built-in. Possibly I've just happened on a bunch of
examples where it does not help, but experiences of a year ago do not
seem to remain valid now. Just wondering if my experience was consistent
with what is expected now in 3.0.2.

Post some details, please.  Are the times in 3.0.2 like the times in
3.0.1 with or without compiling?  Or were you comparing to some other
version?

Duncan Murdoch