/usr/local/MATLAB/R2012a/bin/mex: 1653: gcc: not found

Warning: You are using gcc version "".  The version
         currently supported with MEX is "4.4.6".
         For a list of currently supported compilers see: 
         http://www.mathworks.com/support/compilers/current_release/


    mex:  mex_oe.cc  not a normal file or does not exist.
gcc编译器根本不存在，但是在命令中检测gcc的版本：
yanzhixue@ubuntu:~$ gcc -v
The program 'gcc' can be found in the following packages:
* gcc
* pentium-builder
Try: sudo apt-get install <selected package>
yanzhixue@ubuntu:~$ sudo apt-get install gcc
[sudo] password for yanzhixue: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
gcc is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 208 not upgraded.

再进行检测
yanzhixue@ubuntu:~$ gcc -v
The program 'gcc' can be found in the following packages:
* gcc
* pentium-builder
Try: sudo apt-get install <selected package>

提示已经是新版本了，但是还是提示这个跟没有装似的，陷入了死循环