Unable to install gfortran compiler on yosemite

Hi there,

I was wondering if anyone could assist with the following problems in yosemite. I'm currently using a 2012 macbook pro and I've just upgraded to yosemite (10.10.5). Unfortunately, most upgrades in mac tend to interfere with some key softwares that rely on gfortran. Usually, this is easily resolved by uninstalling and re-installing gfortran. I've done this using the following command:

sudo rm -r /usr/local/gfortran /usr/local/bin/gfortran

I initially installed the 5.2 version but removed this (as it didn't resolve my problem) and then tried to install gfortran 4.5.0. After rebooting, I'm unable to install anymore versions of gfortran due to the following error:

"GNU fortran compiler (gfortran) can't be installed on this disk. A newer version of this software already exists on the disk".

I've tried searching my mac via finder to see if there's any gfortran components remaining. Any ideas how to resolve this? I've read a few posts online but none has been particularly helpful.