FORTRAN

GFortran

Installation

Ubuntu
apt install gfortran
AlmaLinux
dnf install gcc-gfortran
Arch Linux
pacman -S gcc-fortran

Examples

Fibonacci Numbers
program main
    implicit none
    character(255) a
    integer n
    call getarg(1, a)
    read(a,*) n
    print *, fib(n)
contains
    recursive integer function fib(n) result(ret)
        integer n
        if (n < 2) then
            ret = n
        else
            ret = fib(n-2) + fib(n-1)
        end if
    end function fib
end program main

! compile example
!   gfortran -o fib_fortran -O3 fibonacci.f90