Crate nufast 

NuFast

Fast and accurate three-flavor neutrino oscillation probabilities in vacuum and matter.

This is a Rust port of NuFast by Peter Denton, based on the algorithm described in arXiv:2405.02400.

Features

• Vacuum oscillations: Full 3-flavor PMNS oscillation probabilities
• Matter effects (MSW): Constant-density matter with arbitrary electron fraction
• Anti-neutrino mode: Sign-flipped δCP and matter potential
• CP violation: Full δ_CP phase support
• Newton refinement: Optional iterative improvement for matter eigenvalues
• Batch API: VacuumBatch for 45% faster energy spectrum calculations
• Zero dependencies: Pure Rust, no external crates required
• WebAssembly: Zig implementation compiles to WASM (see benchmarks/zig/wasm/)

Quick Start

use nufast::{VacuumParameters, probability_vacuum_lbl};
use std::f64::consts::PI;

let params = VacuumParameters {
    s12sq: 0.307,
    s13sq: 0.0218,
    s23sq: 0.545,
    delta: 1.36 * PI,
    Dmsq21: 7.42e-5,
    Dmsq31: 2.517e-3,
    L: 295.0,
    E: 0.6,
    antineutrino: false,
};

let probs = probability_vacuum_lbl(&params);
assert!(probs[1][0] >= 0.0 && probs[1][0] <= 1.0); // P(νμ → νe)

Performance

Benchmarks on AMD Ryzen (10M iterations):

Language	Vacuum	Matter N=0
Zig SIMD	21 ns	37 ns
Zig	42 ns	108 ns
Rust	61 ns	95 ns
C++	49 ns	130 ns
WASM	80 ns	150 ns

Rust is 27% faster than C++ for matter calculations. Zig SIMD achieves 48M vacuum/sec throughput.

Structs

MatterParameters

Parameters for matter oscillation calculations.

VacuumBatch

Pre-computed vacuum oscillation parameters for batch calculations.

VacuumParameters

Parameters for vacuum oscillation calculations.

Functions

normalize_probabilities

Clamp all probabilities to [0, 1] and ensure row unitarity.

probability_matter_lbl

Calculate matter oscillation probabilities for long-baseline experiments.

probability_vacuum_lbl

Calculate vacuum oscillation probabilities for long-baseline experiments.

Type Aliases

ProbabilityMatrix

3×3 probability matrix type.