Simple FORTRAN

For those of you that suffered through my botched presentation yesterday, here's a small set of files to get you started. I cleaned things up this morning and put together a small package of three FORTRAN files and their associated Makefile. The FORTRAN files should give you a simple skeleton that illustrates a main program that calls a subroutine and then a function. The subroutine and function are each in separate files along with unit test drivers. Throw out the stuff that I gave you yesterday ( use the UNIX 'rm' command ) and then get the new tar archive fort_simple.tar and place it in the directory you worked in yesterday.

Once you have the tar archive, here is the UNIX command to open it:

tar -xvf fort_simple.tar

You can build and then run this simple program with the included makefile by typing( TRY THIS!! ):

make f_simple
f_simple

This version of the Makefile is much simpler that the one I tried to work through during the talk. In particular, this version contains the phrase CUSTOMIZE HERE at the four points where you need to change the Makefile to use with your own program.

Examples of Programming Style

Now you should view each of the FORTRAN files with Xemacs. If you view the files with Netscape (by clicking below), you won't see the language formatting that Xemacs will provide.

These files illustrate the main ideas that I listed under programming style during the talk.

Modular Programming
Both the subroutine and the function are placed in their own modules to illustrate how you work with multiple files. This level of decomposition is only an illustration of how you work with multiple files.
Self Documenting Code
All three modules contain abundant comments explaining what's taking place in the code.
Use the Pre-processor

Using the pre-processor is easier than I led you to believe. The version of f77 on Suns will automatically run the pre-processor on any file with a .F extension. If you just want to look at the pre-processed output, the command
- f77 -F filename.F
will preprocess filename.F and put the result in filename.f. Then you can look at filename.f to see what the pre-processor has actually done ( TRY THIS!! ).
All three modules illustrate uses for the pre-processor. The main program (fort_main.F) uses conditional compilation to selectively include either the subroutine call, the function call or both. At the moment the #defines at the top of 'fort_main.f' enable both the subroutine and the function call. Try removing one of the #defines ( say the #define ILLUSTRATE_FUNCTION_CALL ) and see what happens when you recompile and run the program.
Unit Test Drivers
Both the 'fort_sub.F' and 'fort_fcn.F' modules contain unit test drivers hidden behind the symbol UNIT_TEST. The following make commands to build the unit test drivers ( TRY THIS!! ).
- make fcn_unit
- make sub_unit
Now you can execute the unit test drivers by typing 'fcn_unit' or 'sub_unit'
Leave Debugging code in place
All three module contain debugging statement hidden behind the DEBUG symbol. Compiling any of these modules with #define DEBUG or the -D compiler flag (-DDEBUG) will enable the debugging code.

Simple FORTRAN

Examples of Programming Style

Modular Programming

Self Documenting Code

Use the Pre-processor

Unit Test Drivers

Leave Debugging code in place