PREREQUISITES: XCODE AND COMPILERS
- First of all, install Xcode
- The 'Command Line Tools' package is required: https://developer.apple.com/downloads/index.action?name=for%20Xcode%20-# [1]
- If you need it, install gfortran (a binary is available from the gnu page: https://gcc.gnu.org/wiki/GFortranBinaries#MacOS [2])
Download and decompress PETSc (3.6.1 at the time writing)