zavala92/pysurfacefun: pysurfacefun v2.0.0.
Abstract
pysurfacefun 2.0.0 rebuilds the solver core. Code written for 1.0.1 should run without changes: the 1.0.1 test suite passes on 2.0.0 unmodified. What's new Quadrilateral and triangular patches now share one HPS fast direct solver, and its merges follow a nested dissection of the patch graph. On the Rhino cow mesh (339 patches, n = 12), factorization takes 0.15 s instead of 2.20 s, and a repeated solve takes 5.0 ms instead of 28 ms. The factorization is computed once and reused: L.solve(f), L.solve_many([...]) and L.apply(f) do not refactor. Complex coefficients and right-hand sides are supported, and solve(bc=g) imposes Dirichlet data on open surfaces. Problems with variable coefficients can be written as equations, for example "-div(k*grad(u)) + u = f". New IMEX time steppers: SBDF1 to SBDF4, CNAB1 and CNAB2, and the RK111, RK222 and RK443 schemes of Ascher, Ruuth and Spiteri. They work for single fields and for coupled systems such as "dt(u) - D*lap(u) = N(u, v)". Fields store their values in contiguous arrays. Arithmetic, NumPy ufuncs, derivatives, integrals and norms act on all patches at once. A built-in VTK writer produces binary, compressed VTU and VTP files, about 9 times smaller than the old ASCII files. write_vtu no longer needs meshio. The repository now has continuous integration on Python 3.10 to 3.13, documentation pages on the solver, equations and time stepping, benchmarks, and 84 tests (1.0.1 had 33). Upgrading from 1.0.1 Results change only where 1.0.1 was wrong. The main cases are: normal() is oriented consistently, and outward on closed surfaces. In 1.0.1 it pointed inward on half of the cubed-sphere faces, which also broke hodge on the sphere. On coarse periodic meshes such as torus(n, 2, 4), different edges that share both end points are no longer glued together. parse_pdo sums repeated terms instead of overwriting them, and quadwts(n, kind=1) returns Fejér weights. Hodge components of real fields are returned as real arrays. Triangle nodes with family="lgl" work with NumPy 2.5. Two defaults have changed. VTK files are written in binary, compressed form (pass binary=False for ASCII), and merges follow nested dissection (merge_strategy="natural" restores the old order). The full list of changes is in CHANGELOG.md. Installation python -m pip install "pysurfacefun @ git+https://github.com/zavala92/pysurfacefun@v2.0.0"