You want #RungeKutta methods in #Fortran? I got you covered! #rklib Do link previews work on Mastodon?:
https://github.com/jacobwilliams/rklib
GitHub - jacobwilliams/rklib: Fixed and variable-step Runge-Kutta solvers in Modern Fortran

Fixed and variable-step Runge-Kutta solvers in Modern Fortran - GitHub - jacobwilliams/rklib: Fixed and variable-step Runge-Kutta solvers in Modern Fortran

GitHub