[Rd] How to safely using OpenMP pragma inside a .C() function?

[Paweł Matykiewicz]

>>> .Internal(setMaxNumMathThreads(1)); .Internal(setNumMathThreads(1)); m <-
>>> matrix(rnorm(810000),900,900); system.time(d <- dist(m))
>>>
>>>  user  system elapsed
>>>  3.510   0.013   3.524
>>>
>>> .Internal(setMaxNumMathThreads(5)); .Internal(setNumMathThreads(5)); m <-
>>> matrix(rnorm(810000),900,900); system.time(d <- dist(m));
>>>
>>>  user  system elapsed
>>>  3.536   0.007   1.321

These results are obtained on:

  Model Name:	Mac Pro
  Model Identifier:	MacPro4,1
  Processor Name:	Quad-Core Intel Xeon
  Processor Speed:	2.93 GHz
  Number Of Processors:	2
  Total Number Of Cores:	8
  L2 Cache (per core):	256 KB
  L3 Cache (per processor):	8 MB
  Memory:	12 GB
  Processor Interconnect Speed:	6.4 GT/s
  Boot ROM Version:	MP41.0081.B07
  SMC Version (system):	1.39f5
  SMC Version (processor tray):	1.39f5

Thank you for your comments
Regards
-- 
Pawel Matykiewicz
http://www.neuron.m4u.pl
http://www.linkedin.com/in/pawelmatykiewicz