Python bindings for diffsol

• PyPI: https://pypi.org/project/pydiffsol/
• Documentation: https://pydiffsol.readthedocs.io/en/latest/

import pydiffsol as ds
import numpy as np

# DiffSl code and matrix type specified in constructor
ode = ds.Ode(
    """
    in = [r]
    r { 1.0 }
    k { 1.0 }
    u { 0.1 }
    F { r * u * (1.0 - u / k) }
    """,
    ds.nalgebra_dense
)

# Example overriding r input param with 2.0
params = np.array([2.0])
print(ode.solve(params, 0.4))

# Above defaults to bdf. Try esdirk34 instead
ode.method = ds.esdirk34
print(ode.solve(params, 0.4))

• Instability for BDF with FaerSparse KLU. We are investigating a segfault in underlying diffsol. In the meantime, unit tests are disabled for this combination.

To build locally, create a venv and use maturin to set up your environment, optionally setting diffsol-llvm to your installed LLVM and enable suitesparse if you have it installed (required for sparse matrix types). Also specify dev extras for pytest, running examples and docs image generation. For example:

maturin develop --extras dev --features diffsol-llvm17 --features suitesparse

The .vscode setup includes examples for running tests and examples in python via lldb so underlying rust can be debugged. The build task in tasks.json runs with diffsol-llvm17 and suitesparse and assumes that you have these installed, for example on macos with brew install llvm@17 suite-sparse or for debian-flavoured linux apt install llvm-17 libsuitesparse-dev. If you have a different configuration, you may need to edit tasks.json and settings.json.

The python path is hard-coded in launch.json to .venv/bin/activate (this is the default when running uv in macos or Linux). If you have pip-installed to a different location or running on Windows, you need to edit launch.json.