CentOS : Install 4.4.7 GCC G++ gfortran

cd /etc/yum.repos.d

wget http://people.centos.org/tru/devtools-1.1/devtools-1.1.repo 

yum --enablerepo=testing-1.1-devtools-6 install devtoolset-1.1-gcc* 

This will install everything under  /opt/centos/devtoolset-1.1/root/usr/bin/

to avail it for every particular user specify it in .bashrc file 

export CC=/opt/centos/devtoolset-1.1/root/usr/bin/gcc  

export CPP=/opt/centos/devtoolset-1.1/root/usr/bin/cpp

export gfortran=/opt/centos/devtoolset-1.1/root/usr/bin/gfortran

we can also do this for every users:- 

ln -s /opt/rh/devtoolset-2/root/usr/bin/gfortran usr/local/bin/gfortran

now check it :- gfortran --v 

gcc version 4.7.2 20121015 (Red Hat 4.7.2-5) (GCC)