Compile Fortran using GCC

GCC (shorthand for 'GNU Compiler Collection') is a collection of compilers able to compile multiple different programming languages.

This page describes how to compile Fortran code using the GCC.

Procedure

0. Create a Fortran source file

You will need Fortran code to work on.

In this optional step, a file with a minimal Fortran program is created.

Create and write a Fortran source file called hello_world.f:

nano hello_world.f

In nano, write the Fortran program as such:

C     HELLO.F :  PRINT MESSAGE ON SCREEN
      PROGRAM HELLO
      WRITE(*,*) "hello, world";
      END

1. Load a GCC module

Load a recent GCC module:

module load gcc/13.2.0

Do I really need to load a module?

No, as there is a system-installed GCC.

For sake of doing reproducible research, always load a module of a specific version.

2. Compile the source file

After saving and closing nano, compile as such:

gfortran hello_world.f

This compiles the file hello_world.f using all defaults:

• default/no optimization
• the executable created is called a.out

To compiles the file hello_world.f with run-time speed optimization and creating an executable with a more sensible name, use:

gfortran -Ofast -o hello_world hello_world.f

• -Ofast: optimize for run-time speed, similar to -O3
• -o hello_world: the executable created is called hello_world

3. Run

Run the program:

./a.out 

Output:

hello, world