This release accumulates various small improvements and fixes. A highlight is the new ReactionDiffusionPDE class, which simplifies the definition of typical reaction-diffusion systems. What's Changed Clarified when backends are cached by @david-zwicker in https://github.com/zwicker-group/py-pde/pull/857 Refactor modelrunner integration: streamline hook registration and improve documentation by @david-zwicker in https://github.com/zwicker-group/py-pde/pull/858 Remove commented-out test for automatic backend selection in MPI solvers by @david-zwicker in https://github.com/zwicker-group/py-pde/pull/859 Update installation instructions in README by @Grzyb33k in https://github.com/zwicker-group/py-pde/pull/862 Clarify import error (not warning since exits) message for mpi4py vs. numba_mpi packages by @Grzyb33k in https://github.com/zwicker-group/py-pde/pull/860 Enhance documentation: clarify backend compilation options and update terminology for integrators by @david-zwicker in https://github.com/zwicker-group/py-pde/pull/863 Enhance projection methods in ScalarField and FieldCollection: add support for max and min methods, and update tests accordingly by @david-zwicker in https://github.com/zwicker-group/py-pde/pull/865 Refactor backend return statements and enhance type hints for better clarity and consistency by @david-zwicker in https://github.com/zwicker-group/py-pde/pull/866 Enhance boundary condition handling: add error handling for sequence comparisons and introduce a test for setting array boundaries by @david-zwicker in https://github.com/zwicker-group/py-pde/pull/867 Add type ignore comments for compatibility in various operators and grid classes by @david-zwicker in https://github.com/zwicker-group/py-pde/pull/868 Refactor plot_on_axes and plot_on_figure functions for improved efficiency by @david-zwicker in https://github.com/zwicker-group/py-pde/pull/870 Update README and pyproject.toml for improved clarity and consistency by @david-zwicker in https://github.com/zwicker-group/py-pde/pull/871 Add ReactionDiffusionPDE class and example usage; implement tests for functionality and input validation by @david-zwicker in https://github.com/zwicker-group/py-pde/pull/872 Full Changelog: https://github.com/zwicker-group/py-pde/compare/0.56.1...0.57.0