Mex-file works only in Matlab COMMAND Window

Hi, I thought my mex-code was wrong because it didn't work for some inputs.

But i've just tried to run it from the Matlab Command Window, and it works !

How can this be possible ? Why it works in Command Window, and not in the Matlab Desktop ?

In Matlab Desktop, it doesn't really crash, it just hangs, never stops, I have to kill Matlab to stop it. I thought it was an infinite loop in the mex-code, but it works in command window.

Thanks.

[Andreas Goser]

What does "in the MATLAB Desktop" means? How exactly do you start / invoke it?

[ben]

Matlab Command Window means running >> matlab -nojvm (i.e without java virtual machine).

When I say Matlab Desktop I mean the classic Matlab (with graphic interface).

[Jonathan Sullivan]

Sounds like there may be a bug in your mex file. Most likely a memory management issue.

[ben]

yes maybe, but then, it would be memory issue related to the use of Java Virtual Machine ? I don't get why it works when Java is not used.

Answer 1

[Jan]

If the MEX confuses the memory manager, the results are random. So your observed relation between starting Matlab without Java and the successful run of your program can be an illusion. Even trying it 1000 times will not prove, that the MEX works correctly then.

Answer 2

[ben]

I really tried to debug the mex code, but my conclusion is that it doesn't hang because of a bad loop or something.

The code works in C++, and I ran the two codes (just C++ and in a mexFunction), and it seems the mex-code just stop some steps before the end, and Matlab begin to hang.

[James Tursa]

I'm in agreement with Jan ... sounds like a bug in your code.

Answer 3

[ben]

When you run Matlab (with java), does the computation use the memory of the Java Virtual Machine ?

[ben]

It doesn't make sense, the C++ run of the same code run fast and seems to use just a bit of memory. But when java is enabled in Matlab, the memory use seems big.

If I increase the Java heap limit, the memory use increases too (still hanging).

I don't get where (in which kind of situations) Java could use or leak more memory than a simple C++ run.