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From: Rune Allnor on 29 Jun 2010 07:32
On 29 Jun, 01:19, "Joseph Cohen" <hypergra...(a)hotmail.com> wrote:
> I have an m-file function that uses a for-loop that repeats many times. Unfortunately, it runs rather slowly. I heard that transforming it into a MEX file could possibly speed it up. I tried doing this automatically using the mcc -x command, but got this message:
>
> rror using ==> mcc
> Error: -x is no longer supported. The MATLAB Compiler no
> longer generates
>   MEX files because there is no longer any performance
>   advantage to doing so: the
>   MATLAB JIT accelerates M-files by default.
>   To hide proprietary algorithms, use the PCODE functi
>
> Is the fact that "there is no longer any performance advantage to doing so" correct? Or should I go ahead and manually create a MEX file anyway?

MEX *might* be significantly faster than matlab m code (some
10-50-100x faster is not unheard of) *provided*

1) The problem at hand is sufficiently different from what
matlab is tuned to deal with (i.e. there is little linear
algebra involved)

2) The MEX (C, C++ or Fortran) programmer really knows what
he is doing.

Don't expect to gain anything ofsignificance merely by hacking
some naive C(++) code. Certainly don't expect to gain anything
by applying automized tools based on naive m code.

Rune
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