错误：
This error was detected while a MEX-file was running. If the MEX-file is not an official MathWorks function, please examine its source code for errors. Please consult the External Interfaces Guide for information on debugging MEX-files.
Matlab要求强制退出
解决办法：
简单粗暴，重新编译Matconv
1.编译(有时候需要： mex -setup）
>>vl_compilenn
2.启动
>>vl_setupnn
3.测试
>> vl_testnn