Using Fortran in the SageMathCloud

This is a demo of how to create a standalone Fortran program in the SageMathCloud (https://cloud.sagemath.com). 1. Create a file sum.f90, which I copy and paste from http://en.wikibooks.org/wiki/Fortran/Fortran_examples#Area_Of_a_Triangle_program 2. Create a terminal and type "gfortran sum.f90" 3. Run the program by typing "./a.out".