Apple - How to Install Octave in El Capitan?

From my homebrew:

brew info octave
homebrew/science/octave: stable 4.0.0 (bottled), HEAD
high-level interpreted language for numerical computing  
https://www.gnu.org/software/octave/index.html
Not installed

and

brew cask info octave
octave: 3.8.2-1
Octave
https://gnu.org/software/octave/
Not installed

xoctave is a gui which I suspect is independent. I'd use homebrew for the installation.

FWIW the Octave wiki it explains what to do:

brew tap homebrew/science
brew update && brew upgrade --all
brew install octave

if you have already installed gcc...

sudo chown -R (username):admin /usr/local/lib/gcc/

and

brew install octave

after this, you make cross fingers...