按matconvnet官网上的步骤来，编译代码的时候会发现编译失败。
参考这条issues
以下是我的解决方案：
I use ubuntu16.04 with x64 architecture. I installed matlab2016b, with cuda7.5 and cudnn5 installed.
I faced with similar problem and handle it by executing these commands:(for me, default gcc is version 5.4)
cd /usr/local/MATLAB/R2016b/sys/os/glnxa64 #where I installed my matlab
sudo mv libstdc++.so.6.0.20 bak-libstdc++.so.6.0.20
sudo mv libstdc++.so.6 bak-libstdc++.so.6
sudo ln -sf /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21 ./
sudo ln -sf ./libstdc++.so.6.0.21 ./libstdc++.so.6
Then reopen matlab and compile MatConvNet. Still have warning about gcc version but compiling can be done.