清空筛选条件
清空筛选条件

problem executign mex file

3 次查看（过去 30 天）
michael
michael 2013-9-28
评论： Jan 2013-9-30
Hello,
I've wrote some mex file, compiled it without any problem, but have problem to run it. Every time when I'm executing it, I'm getting an some internal matlab error and that i need to close matlab.
Can somebody go over the code and find the source of the problem? (I guess it is in the return parameters)
BR
  3 个评论
显示 1更早的评论
Kaustubha Govind
Kaustubha Govind 2013-9-30
You might want to debug your MEX-file and isolate the line numbers causing the crash.
Jan
Jan 2013-9-30
@michael: Did you see my question?

请先登录，再进行评论。

请先登录，再回答此问题。

回答（2 个）

Image Analyst
Image Analyst 2013-9-28
Anytime you get that error, where the whole of MATLAB comes crashing down in a fiery mess, you need to call the Mathworks. Even if there were a problem with your code, it shouldn't bring the whole MATLAB program down.
  3 个评论
显示 1更早的评论
Image Analyst
Image Analyst 2013-9-28
Their program should handle it gracefully. You're running the mex file from MATLAB - from an m-file - right? Not from some other program. I can see no circumstances where it would be acceptable for their whole program (MATLAB) to shutdown rather than just your m-file. If your program causes problems in Microsoft Visual Studio, you don't see Visual Studio come crashing down, do you? Of course not, so neither should MATLAB.
Jan
Jan 2013-9-28
编辑：Jan 2013-9-28
No, I do not agree. You can easily confuse the memory manager in a MEX file, e.g. by writing to X[4], when the array X has less elements. Therefore it is very easy to let Matlab crash from inside a MEX function, even to an arbitrary later time. Example:
plhs[0] = mxCreateDoubleMatrix(1, 5, mxREAL);
mxSetData(plhs[0], malloc(5 * sizeof(double));
This leaks memory and let Matlab crash, when the replied variable is cleared from the memory.

请先登录，再进行评论。

Jan
Jan 2013-9-28
编辑：Jan 2013-9-28
This should cause severe problems:
output_data_len = (int) mxGetData(prhs[2]);
mxGetData replies a void * pointer and converting it to int will produce different results on a 32 and 64 bit machine. But in both cases you get the pointer to the data, not the value of the first element. Perhaps you mean:
output_data_len = (int) mxGetScalar(prhs[2]);
You use output_data_len here:
decision = (double*) malloc(output_data_len * sizeof(double))
But if output_data_len is the address, this should reply a NULL pointer. Better use mxMalloc, which care for such problems, or (better and) check the replied pointer.
Finally, this will confuse Matlab's memory manager massively:
plhs[0] = mxCreateDoubleMatrix(1, output_data_len, mxREAL);
mxSetData(plhs[0], decision);
On one hand mxCreateDoubleMatrix allocates memory for the data already. mxSetData overwrites the pointer to these data, such that the memory is leaked. Then the memory for the data in plhs[0] has been created by malloc, but inside Matlab it is released by mxFree. This must crash Matlab's memory manager.
I guess, you want something like:
output_data_len = (mwSize) mxGetScalar(prhs[2]);
plhs[0] = mxCreateDoubleMatrix(1, output_data_len, mxREAL);
decision = mxGetPr(plhs[0]);
Equivalent changes are required for all other "(int) mxGetData" calls.

类别

在 Help Center 和 File Exchange 中查找有关 Debugging and Analysis 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by