FPM-ODEPACK Demonstration

Background

This project is a demonstration of methods meant to mimic certain aspects of large physics codes. Namely,

1. The core calculation is a FORTRAN program using ODEPACK solvers.
2. Parameters of the simulation can be adjusted using an input FORTRAN namelist (.nml file).
3. There's a python wrapper running the FORTRAN code and plotting the resulting data.

Instead of trying to compile/link the source code of ODEPACK myself (written in f77), I used the Fortran Package Manager (FPM) framework with this FPM dependnacy.

This allows us to use the LSODA routine within a Modern Fortran program. Originally I did try to compile and link ODEPACK but I ran into problems because the gfortran compiler on my machine wouldn't cross-compile the 2018 fortran standard and the f77 used by ODEPACK. In the future I could look into the linked FPM dependancy to determine how they created a modern fortran interface for the f77 routines.

Installation/Building

I went with the conda method of installing FPM (outlined on the FPM website). Personally I installed it under a new conda environment called fpm (this is relevant when it comes time to run the fortran program from a python file which might rely on a separate conda enviornment).

To build the project under the FPM framework one can use:

fpm build

Building the project will also run the test-series. The test-series covers certain subroutines in the ./src folder. Furthermore it will write a sample input.nml file as part of the tests. The tests can also be manually run with: fpm test.

To run the fortran program one can use,

fpm run -- -i mynamelist.nml -o output.dat

Example Usage

... to be written.