>> vl_compilenn
警告: CL.EXE not found in PATH. Trying to guess out of mex setup.
> In vl_compilenn>check_clpath (line 650)
In vl_compilenn (line 426)
'cl.exe' 不是内部或外部命令，也不是可运行的程序
或批处理文件。
错误使用 vl_compilenn>check_clpath (line 656)
Unable to find cl.exe
出错 vl_compilenn (line 426)
cl_path = fileparts(check_clpath()); % check whether cl.exe in path
问题在https://github.com/vlfeat/matconvnet/issues/650有解决办法
the problem is with the visual studio setup folder layout
The matconvnet 'vl_compilenn' is trying to find for cl.exe in 'C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\bin\amd64'. which has changed with new setup of visual studio.
If you have installed latest versions of Visual studio try searching for the 'cl.exe' in the subfolders below 'C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC'
eg: when i searched 'cl.exe' ; i found it under 'C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.13.26128\bin\Hostx86\x86'
so for above path i replace the variable 'cl_path' in 'vl_compilenn' line 646 (function- check_clpath)
from --> cl_path = fullfile(cc.Location, 'VC', 'bin', 'amd64'); (in matconvnet beta 25)
to --> cl_path = fullfile(cc.Location, 'VC', 'Tools','MSVC','14.13.26128','bin','Hostx64','x64');
let me know if it works
14.13.26128改你的文件名（相同就不用改）
在vl_compilenn.m中修改改行代码
cl_path = fullfile(cc.Location, 'VC', 'Tools', 'MSVC','14.16.27023','bin','Hostx64','x64');
问题就解决了