Python wrapper for martinjrobins diffsol ODE solver library
Note: this is in a pre-release state and wheels are not built yet. Leading up to the initial release, the best way to run is to clone this repo and open the folder in VSCode. Follow the prompts to open in a dev container which will set up build dependencies from the Dockerfile and VSCode extensions for local development.
The project uses PyO3 maturin so a build and tests can be run with:
$ maturin develop --extras test
$ pytest
Additionally, launch.json contains a debug configuration for debugging Rust
code in VSCode whilst a Python script is running. To use this put breakpoints on
the code Rust you want to interrogate and launch Run Python Example.
The Rust API supports many matrix and solver types which are determined at compile time when working in Rust. However, in order to build a Python wheel the types need to be known up front. Currently py-diffsol has pre-baked the following matrix-solver pairings:
nalgebra_dense_lu_f64faer_sparse_lu_f64faer_sparse_klu_f64
Each name has four parts: 1) the matrix library; 2) whether the matrix is dense
or sparse; 3) the solver (currently LU or KLU); 4) the underlying scalar type.
The name is the submodule in diffsol that contains the various solver methods
and it is often convenient to import these with an alias, for example:
from diffsol import faer_sparse_lu_f64 as ds
$ maturin develop
$ python
>>> from diffsol import nalgebra_dense_lu_f64 as ds
>>> context = ds.Context(
... """
... in = [a]
... a { 1 }
... u { 1.0 }
... F { -a*u }
... out { u }
... """
... )
>>> builder = ds.Builder().rtol(1e-6).p([0.1]).h0(5.0)
>>> problem = builder.build_diffsl(context)
>>> solver = ds.Bdf()
>>> result = solver.solve(problem)
>>> print(result.t, result.y)
To build against a specific LLVM version, set the LLVM_SYS_160_PREFIX and LLVM_DIR environment variables.
To run cargo test, set PYTHONPATH to the location of your venv site packages to distinguish from the system environment.
For example, a native macOS build with a local venv could be configured with a .cargo/config.toml file containing:
LLVM_SYS_160_PREFIX = "/opt/homebrew/opt/llvm@16"
LLVM_DIR = "/opt/homebrew/opt/llvm@16"
PYTHONPATH = "venv/lib/python3.12/site-packages"