HP Fortran Programmer's Reference (September 2007)

Program units and procedures
Modules
Chapter 7 197
END DO
END SUBROUTINE back_substitution
END MODULE linear_equation_solver
Here are the command lines to compile and execute the program, along with the output from
a sample run:
$ f90 precision.f90 lin_eq_slv.f90 main.f90
$ a.out
The solution: 1.0 2.0 3.0
The order in which the files appear on the f90 command line is significant: files that contain
modules must be compiled before files containing the program units that use the modules. For
more information about compiling programs that use modules, see the
HP Fortran Programmer’s Guide