multicalc 0.9.0

Math for real-time embedded systems, in stable no_std Rust: state estimation, control, kinematics, Lie groups, autodiff, and linear algebra — from 64-bit servers to bare-metal microcontrollers
Documentation 
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//! Spatial math: rotations, Lie groups, and spatial-algebra types.
//!
//! - [`Quaternion`] — unit-quaternion rotations.
//! - [`SO2`] / [`SO3`] / [`SE2`] / [`SE3`] — 2D/3D rotation and rigid-transform Lie groups.
//! - [`Twist`] / [`Wrench`] — spatial velocity and force in `[v; ω]` / `[force; torque]` ordering.

use crate::scalar::Numeric;

mod lie;
mod quaternion;
mod twist;
mod wrench;

pub use lie::{SE2, SE3, SO2, SO3};
pub use quaternion::Quaternion;
pub use twist::Twist;
pub use wrench::Wrench;

/// Angle threshold below which trig ratios switch to their Taylor series.
/// Also used for eps-scale proximity checks (e.g. Euler gimbal lock vs ±1).
/// Scaled as `30 · EPSILON` so each scalar type gets a type-appropriate cutoff.
#[inline]
pub(crate) fn small_angle<T: Numeric>() -> T {
    T::EPSILON_X30
}

/// Squared small-angle threshold, `(30 · EPSILON)²`, for branches on θ² / ‖v‖² before
/// `sqrt`.
#[inline]
pub(crate) fn small_angle_sq<T: Numeric>() -> T {
    small_angle::<T>() * small_angle::<T>()
}