Feature/Documentation: Fortran implementation, fpm manifest, and updated README.md

[rouson]

What type of PR is this? (check all applicable)

• Feature
• Example
• Documentation
• Test

Description

This PR makes a fresh pass at adding Fortran implementations in a minimally intrusive way:

1. A new git submodule,
2. A new fpm.toml file that requires no additional files or soft links, and
3. An updated README.md describing the cloning, installing, testing, and examples for the Fortran implementation.

As before, the fpm.toml file builds the C++ and Fortran implementations and their prerequisites.

Related Issues & Documents

This PR supercedes all previous PRs related to the now-deleted dev/fortran branch.

QA Instructions, Screenshots, Recordings

With git and fpm installed on macOS, Linux, or Windows, and with the formal branch checked out and your present working directory set to MOLE's root directory, run the following commands:

git switch formal
git submodule update --init --recursive
fpm install --profile release
fpm test --profile release
fpm run --example --profile release

fpm can be installed via package manager or by compiling one source file and putting the resulting executable file in your PATH.

Added/updated tests?

• Yes

Read Contributing Guide and Code of Conduct

• I have read and followed the Contributing Guide and the Code of Conduct

Are there any post deployment tasks we need to perform?

No.

What gif best describes this PR or how it makes you feel?

[jbrzensk]

I checked this out, and it works great. I hit the same issues as last time, where I had to include

--flag "-ffree-line-length-none -fcoarray=single"

at the end of every command I ran, because of errors with GNU gfortran 13.3.0. A note in the README would be nice to address the coarray part. I note your README has the free-line-length mentioned.

I am going to bring this up with the MOLE group today. You implemented a few things we have never done before:

• Linking another repository with submodules
• "renaming" MOLE to formal in your repo ( not a bad thing, just like with PyMOLE )
• Separate set of examples ( again, not a bad thing, just something to discuss )

Overall, I really like it, and really like the testing you have. We really need something like that for the C++ and MATLAB codes.

[jbrzensk]

My Workflow to run this

• clone repo
• git switch formal
• git submodule update --init --recursive
• fpm install --flag "-ffree-line-length-none -fcoarray=single"
• fpm test --flag "-ffree-line-length-none -fcoarray=single"
• cd src/fortran/example
• fpm run --example div-grad-laplacian-1D --flag "-ffree-line-length-none -fcoarray=single"
• fpm run --example extended-gauss-divergence --flag "-ffree-line-length-none -fcoarray=single"

[rouson]

@jbrzensk thanks for testing this out and for all the helpful feedback. Ifyou use --profile (e.g., --profile release or --profile debug), then fpm should automatically include the -fcoarray=single for you.

[rouson]

@jbrzensk sorry. I missed that you already found the -ffree-line-length-none flag in the README so I just deleted that part of my previous response.

[rouson]

@jbrzensk I just edited the git commands in this PR's original comment to include git switch formal and --profile release.

[rouson]

There's a lot more that fpm could be doing with some effort. For example, it might be able to run the C++ test suite. I made a quick attempt to add features, but didn't succeed. It would be a great project for a student if anyone is interested.