[R] speed issue in simulating a stochastic process

Rolf Turner r.turner at auckland.ac.nz
Fri Nov 7 01:17:13 CET 2014


> On Thu, Nov 6, 2014 at 2:05 PM, Matteo Richiardi <matteo.richiardi at gmail.com
>> wrote:


>> Final question: in your code you have mean(M[t-1L,]): what is the 'L'
>> for? I removed it at apparently the code produces the same output...


The constant "1L" is stored as an integer; the constant "1" is stored as 
double precision.  This sometimes makes no difference and sometimes 
makes a huge difference (especially in the context of numerical 
comparisons).  If something is supposed to be an integer it is safer to 
use the "L" form.

See ?NumericConstants.


Rolf Turner

Rolf Turner
Technical Editor ANZJS

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