[Rcpp-devel] Rcpp Timer

[Jonathan Christensen]

Hi Kaspar and Dirk,

It is indeed cumulative. Previously (presumably when that gallery page was
written) it was not cumulative, but Romain Francois changed the behavior of
the step() function several years ago, in this commit:
https://github.com/RcppCore/Rcpp/commit/e295b2b178de55291e63705966368404bb0ce5e1
.

There is no indication or reasoning about changing the behavior, so it may
be that making it cumulative was unintentional.

Jonathan

On Thu, Dec 29, 2016 at 8:23 AM, Dirk Eddelbuettel <edd at debian.org> wrote:

>
> On 29 December 2016 at 14:55, Kaspar Märtens wrote:
> | Hi,
> |
> | Trying out the Rcpp Timer example from http://gallery.rcpp.org/articles/
> | using-the-rcpp-timer/ I was unable to reproduce similar results. The
> example
> | output
> |
> |     get/put g/p+rnorm()  empty loop
> |   1.967e+03   3.288e+03   6.400e-04
> |
> | compared to the output I see
> |
> |     get/put g/p+rnorm()  empty loop
> |    733.5265   1884.9589   1884.9601
> |
> | Suspiciously, the empty loop appears to take the longest. Could these be
> | cumulatively measured times here?
>
> It is possibly that there is a thinko / bug / error somewhere.  I just
> re-ran
> it via sourceCpp() [ see below ] which is pretty much what Ruby + Jekyll do
> to build the Rcpp Gallery pages.
>
> The results will reflect the underlying machines a little but the
> difference
> you show is much starker.  What is your OS / compiler?   Ubuntu 16.04 with
> g++-5.3 here; page was original written with an older g++.
>
> Dirk
>
>
> Copy and paste below (and I just removed two lines pertaining to ESS which
> do
> no matter here).
>
> R version 3.3.2 (2016-10-31) -- "Sincere Pumpkin Patch"
> Copyright (C) 2016 The R Foundation for Statistical Computing
> Platform: x86_64-pc-linux-gnu (64-bit)
>
> R is free software and comes with ABSOLUTELY NO WARRANTY.
> You are welcome to redistribute it under certain conditions.
> Type 'license()' or 'licence()' for distribution details.
>
>   Natural language support but running in an English locale
>
> R is a collaborative project with many contributors.
> Type 'contributors()' for more information and
> 'citation()' on how to cite R or R packages in publications.
>
> Type 'demo()' for some demos, 'help()' for on-line help, or
> 'help.start()' for an HTML browser interface to help.
> Type 'q()' to quit R.
>
> R> library(Rcpp)
> R> sourceCpp("~/git/rcpp-gallery/src/2013-01-06-using-the-rcpp-timer.cpp")
>
> R> useTimer()
>     get/put g/p+rnorm()  empty loop
>     1620.67     3973.43     3973.44
> R>
>
>
> --
> http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org
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