unitstep.net » matlab http://unitstep.net the home of peter chng Sun, 30 Nov 2008 23:12:11 +0000 http://wordpress.org/?v=2.6.5 en Getting Matlab to run on a newer Athlon 64 (X2) CPU http://unitstep.net/blog/2006/08/21/getting-matlab-to-run-on-a-newer-athlon-64-x2-cpu/ http://unitstep.net/blog/2006/08/21/getting-matlab-to-run-on-a-newer-athlon-64-x2-cpu/#comments Tue, 22 Aug 2006 00:46:20 +0000 Peter Chng http://unitstep.net/blog/2006/08/21/getting-matlab-to-run-on-a-newer-athlon-64-x2-cpu/ I recently installed Matlab v7.0 (R14) on my new computer and ran into some troubles. After starting Matlab, the program window would open as normal, but then it would shutdown almost immediately, usually after about a second or so delay, allowing me to tantalizingly see that it almost working. I did a search and found this helpful article on how to fix the problem.

The issue (Matlab closing right after start-up) stems from Matlab (at least this version, the newer versions might not be affected) not “recognizing” the processor string for newer AMD Athlon 64-based processors; in my case, I had an Athlon 64 X2 3800+. Matlab relies on different Basic Linear Algebra Subprograms (or BLAS) routines for different types of CPUs, and these are stored in different DLL files.

The BLAS file responsible for telling Matlab which DLL file to use for what type of CPU is located at:

%MATLAB7%\bin\win32\blas.spec
(where %MATLAB7% is the path to your Matlab installation)

To fix the problem, open up the file in a text-editor, and add the following two lines to the bottom:

AuthenticAMD Family 15 Model 12 atlas_Athlon.dll # Athlon 64 (Newcastle)
AuthenticAMD Family 15 Model * atlas_Athlon.dll # AMD64

This will tell Matlab to use the proper DLL file with your newer AMD-64-based CPU, instead of apparently defaulting to using a Pentium DLL file when an unrecognized CPU is detected.

More on the problem

As mentioned, the problem stems from the CPU being unrecognized by Matlab’s configuration file. All CPUs have some sort of identifier string, and Matlab uses this to determine what DLL file to use. When an unrecognized CPU string is detected, it apparently defaults to using a Pentium DLL file; this results in Matlab crashing when it’s run on an AMD-64-based CPU, and results in the crash-on-start behaviour.

Why the different DLL files for different CPUs? My guess is that the BLAS, upon which Matlab is based, are optimized or made to work better with select CPUs. It should be noted that these problems may not be experienced if you’re running a more current version of Matlab.

I did a little more searching and found this forum thread over at the Matlab website, where a different fix for the same problem is presented. It involves setting a Windows environment variable instead of editing the blas.spec file, but should do the same thing; I haven’t tried it. This other forum thread also details a similar procedure.

Hope this helps in fixing any Matlab ailments you might have had, because running into a problem like this can be frustrating as heck when you need to have an assignment done for tomorrow!

Update

I’d just like to say that a dual-core setup totally rocks. It’s awesome to be able to still play CS:S while running a Matlab simulation.

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