[R] How to speed up R program

[MAURICE Jean - externe]

Hi Ragia,

If time is really a big problem and you have a lot of datas and you want to use all the cores of the processor, you should use FORTRAN for your calculations. But this is only possible with a real FORTRAN developer and will take some times.

I am an old freelance (61) and I began computing in 1974 with FORTRAN ! I have been hired by a large company in France to translate calculations to FORTRAN. First try : we went from 20 minutes to less than 5 seconds. So it's worth. BUT it is complicated. R is a very permissive and 'near the human' language (I work with hydrological engineers and they can build large R programs) at the opposite, FORTRAN can only do calculations but it does them very very quickly and you must be aware of the hardware on witch you are working and you must take care of integer / real, real4 and real8, .... It's REALLY a computer language.

'modern' FORTRAN are able to use all the cores of the processor and then to have 100% cpu usage. It's INTEL OMP, MPI library, ... but it is another big step.

So it's another way but a difficult one.

Jean in France

PS I spoke of Fortran, but good results can be done with C : C calculations are a little slower than FORTRAN but C possibilities are a lot more 'great' than FORTRAN.
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