topic Re: MKL DFT with Matlab MEX application: environment variable in Intel® oneAPI Math Kernel Library

MKL DFT with Matlab MEX application: environment variable needed

mbackues — Mon, 23 Jun 2008 12:44:09 GMT

Hello. I'm trying to use MKL DFT's in a MEX application. I recall from a few years backthat there's an environment variable that needs to be set, but I don't remember the reasonor exactly what it is, and can't find it online. Without it,Matlab crashes during the FFT plan creation. If someone can remind me what the variable is, I would appreciate it. I am using Matlab 7 and MKL 10.

Re: MKL DFT with Matlab MEX application: environment variable

Dmitry_B_Intel — Mon, 23 Jun 2008 13:00:50 GMT

Hi. Was the variable related to memory management or threading? MKL User's Guide is the place where to look for environment variables, particularly section 6.

Thanks,
Dima

Re: MKL DFT with Matlab MEX application: environment variable

mbackues — Mon, 23 Jun 2008 13:20:03 GMT

Thanks, no, its not one of those threading or memory management environment variables. Its a patch for some kind of incompatibility betweenthe MKL DFT library and MEX libraries. Apparently Matlab isn't high enough on Intel's radar forMEX usebe tested and supported, and vice versa, so its not in the documentation. I don't remember how I found out aboutit before.

Re: MKL DFT with Matlab MEX application: environment variable

mbackues — Tue, 24 Jun 2008 13:46:40 GMT

OK, I have more information....the problem is that Matlab now uses MKL, so the need is to set the environment so that the MEX application can also link in MKL without a conflict. Still don't know how to do that though.

Re: MKL DFT with Matlab MEX application: environment variable

Todd_R_Intel — Thu, 26 Jun 2008 21:46:29 GMT

I'm afraid I don't know. Do you remember if it was an MKL or Matlab variable?

Anybody on the forum familiar with this variable for use of MKL with Matlab?

Re: MKL DFT with Matlab MEX application: environment variable

rbarron — Fri, 27 Jun 2008 13:18:45 GMT

I suggest you post your question on Mathworks forum,

http://www.mathworks.com/matlabcentral/newsreader/

but first do a search on MKL.

Re: MKL DFT with Matlab MEX application: environment variable

AndrewC — Mon, 30 Jun 2008 15:49:09 GMT

The problem is probably that Matlab 7 uses MKL 9.x... and if your MEX DLL uses MKL 10.0 you will crash as there are a number of conflicts. When running in Matlab the ./bin directory ( with the MKL 9.x DLL's) is always first in the PATH.

I have battled with this for some time. There are a couple of solutions however.

1) Link MKL statically into your MEX DLL.

2) Build a 'custom' MKL DLL following the instructions in the MKL documentation, and link your MEX DLL against that. That way, your MEX DLL can load the custom MKL DLL and Matlab will load it's MKL DLL's and there is no longer any conflict.