use-linear

Install

[dependencies]
use-linear = "0.0.1"

Foundation

use-linear provides a deliberately small numeric linear-algebra surface for 2D vectors and 2×2 matrices. The first slice includes a Vector2 type, a Matrix2 type, dot products, matrix-vector and matrix-matrix products, and explicit solving of small linear systems through LinearError. The crate stays close to ordinary f64 math instead of introducing a large generic tensor framework.

Helper group	Primary items	Best fit
Vector operations	`Vector2`, `dot`	Small numeric code that needs explicit 2D linear operations
Matrix operations	`Matrix2`	Call sites that need compact 2×2 products, determinants, and trace values
Solves and error handling	`solve_2x2`, `LinearError`	Small systems where singular behavior should stay explicit

When to use directly

Choose use-linear directly when vector and matrix utilities are the only surface you need and you want to keep that concern narrower than the umbrella facade.

Scenario	Use `use-linear` directly?	Why
You need 2D numeric vectors and 2×2 matrices	Yes	The current surface already covers the common small linear-algebra cases directly
You need explicit handling of singular 2×2 solves	Yes	The API keeps failure visible through `LinearError`
You also need geometry, calculus, or other math domains	Usually no	`use-math` can compose the concrete surfaces behind features

Scope

The current surface is intentionally small and concrete.
Helpers stay focused on f64-based 2D vectors and 2×2 matrices instead of a broader generic tensor framework.
Geometry-specific spatial types and broader algebraic traits belong in adjacent focused crates.

Examples

Vector and matrix products

use use_linear::{Matrix2, Vector2, dot};

let vector = Vector2::new(3.0, 4.0);
let other = Vector2::new(-2.0, 1.0);
let matrix = Matrix2::new(2.0, 1.0, 5.0, 3.0);

assert!((dot(vector, other) + 2.0).abs() < 1.0e-12);
assert!((vector.magnitude() - 5.0).abs() < 1.0e-12);
assert_eq!(matrix.mul_vector(Vector2::new(1.0, -1.0)), Vector2::new(1.0, 2.0));
assert_eq!(matrix * Matrix2::identity(), matrix);

Solving a 2×2 system

use use_linear::{Matrix2, Vector2, solve_2x2};

let matrix = Matrix2::new(2.0, 1.0, 5.0, 3.0);
let rhs = Vector2::new(1.0, 2.0);

assert_eq!(solve_2x2(matrix, rhs)?, Vector2::new(1.0, -1.0));
# Ok::<(), use_linear::LinearError>(())

Status

use-linear is a concrete pre-1.0 crate in the RustUse docs surface. The API remains intentionally small while adjacent geometry and algebra crates continue to grow around it.

use-linear 0.0.2