[R] System.time

Gavin Simpson gavin.simpson at ucl.ac.uk
Thu Feb 12 10:28:41 CET 2009

On Wed, 2009-02-11 at 18:49 -0600, John Kerpel wrote:
> Hi folks!
> Does anyone know why I might see something like this after running
> system.time?
> system.time(svd(Mean_svd_data))
>    user  system elapsed
>       0       0       0
> The data set is tiny and the function returns results instantly, but
> shouldn't it still give me a time?

Jim has already suggested why this might be the case. When I'm testing
the speed of things like this (that are in and of themselves very quick)
for situations where it may matter, I wrap the function call in a call
to replicate():

system.time(replicate(1000, svd(Mean_svd_data)))

to run it 1000 times, and that allows me to judge how quickly the
function executes.



> Thanks,
> John
> 	[[alternative HTML version deleted]]
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