howzat 0.2.0.post1

High-performance polytope backends via Rust FFI bindings to howzat

howzat

User-friendly Python bindings for the Rust crate howzat via PyO3.

Usage

import numpy as np
import howzat

verts = np.asarray([[0.0, 0.0], [1.0, 0.0], [0.0, 1.0]], dtype=np.float64)

res = howzat.solve(verts)  # cached default backend: "snap@howzat-dd:f64"
# res = howzat.Backend().solve(verts)  # same as above
# res = howzat.Backend("howzat-lrs:rug").solve(verts)  # explicit backend

print(res.facets, res.ridges)
print(res.facet_adjacency)

Input vertices must be a contiguous (C-order) numpy.ndarray of float64 with shape (n, d).

Backends

The class howzat.Backend(spec) accepts backend spec strings, which specify the algorithm and parameters of the computation pipeline.

At a high level, the syntax is: [PURIFIER@]KIND[:SPEC]. Some examples:

• snap@howzat-dd:f64 (default)
• howzat-dd:f64
• howzat-dd:f64[eps[1e-12],max]-resolve[rugrat]
• cddlib:gmprational
• cddlib+hlbl:f64
• lrslib+hlbl (defaults to lrslib+hlbl:gmpint)

FIXME: give a complete enumeration of the options and modes.

API

• howzat.solve(vertices) -> SolveResult Convenience function which uses the default backend (snap@howzat-dd:f64).
• howzat.Backend(spec: str | None = None) Loads the specified backend; None selects the default.
• Backend.solve(vertices) -> SolveResult Runs the backend synchronously, single-threaded on the provided vertex set, returning a SolveResult.

SolveResult

A SolveResult has the fields:

• spec: str backend spec actually used
• dimension: int ambient dimension d
• vertices: int number of vertices n
• facets: int number of facets
• ridges: int number of ridges (edges in the facet adjacency / FR graph)
• total_seconds: float time spent inside the backend (seconds)
• vertex_positions: list[list[float]] | None vertex coordinates if the backend returned baseline geometry
• vertex_adjacency: list[list[int]] vertex adjacency lists (length vertices)
• facets_to_vertices: list[list[int]] for each facet, the incident vertex indices
• facet_adjacency: list[list[int]] facet adjacency lists (FR graph)
• fails: int backend-specific failure count (pipeline dependent)
• fallbacks: int backend-specific fallback count (pipeline dependent)

Install

From PyPI:

python -m pip install howzat

Force a local source build, and enabling CPU-native codegen:

RUSTFLAGS="-C target-cpu=native" python -m pip install --no-binary howzat howzat

Prebuilt wheels are compiled for a portable baseline CPU (not target-cpu=native).