Fixed-point mathematical functions which are accurate, deterministic, and guaranteed not to panic.
use fixed::types::I16F16;
use fixed_analytics::{sin, cos, sqrt, ln};
let angle = I16F16::from_num(0.5);
let (s, c) = (sin(angle), cos(angle));
let root = sqrt(I16F16::from_num(2.0)).unwrap();
assert!((root.to_num::<f32>() - 1.414).abs() < 0.001);
let log = ln(I16F16::E).unwrap();
assert!((log.to_num::<f32>() - 1.0).abs() < 0.01);Requires Rust 1.95 or later.
[dependencies]
fixed_analytics = "2.1.0"For no_std environments:
[dependencies]
fixed_analytics = { version = "2.0.1", default-features = false }Total functions return T directly and handle all inputs, possibly with saturation.
Fallible functions return Result<T, Error> and fail on domain violations.
| Category | Total Functions | Fallible Functions |
|---|---|---|
| Trigonometric | sin, cos, tan, sin_cos, atan, atan2 |
asin, acos |
| Hyperbolic | sinh, cosh, tanh, sinh_cosh, asinh |
acosh, atanh, acoth, coth |
| Exponential | exp, pow2 |
ln, log2, log10 |
| Algebraic | — | sqrt |
Functions are calculated via polynomial evaluation, CORDIC, and Newton-Raphson techniques. Complete absence of panic is verified at the linker level via the no-panic crate.
The following total functions saturate, clamping to the representable range near the following thresholds.
| Function | I16F16 Threshold | I32F32 Threshold | Result |
|---|---|---|---|
exp |
x ≥ 10.4 | x ≥ 21.5 | T::MAX |
exp |
x ≤ -11.1 | x ≤ -22.2 | Zero |
pow2 |
x ≥ 15.0 | x ≥ 31.0 | T::MAX |
pow2 |
x ≤ -16.1 | x ≤ -32.1 | Zero |
sinh |
|x| ≥ 11.1 | |x| ≥ 22.2 | T::MAX or T::MIN |
cosh |
|x| ≥ 11.1 | |x| ≥ 22.2 | T::MAX |
tan |
|x - pole| < 4e-5 | |x - pole| < 5e-10 | T::MAX or T::MIN |
Where for tan, "pole" refers to ±π/2, ±3π/2, ±5π/2, ...
Relative error statistics measured against MPFR reference implementations. Accuracy regressions are not permitted; every change is benchmarked against the baseline before merging. The file tools/accuracy-bench/baseline.json contains further measurements.
| Function | I16F16 Mean | I16F16 Median | I16F16 P95 | I32F32 Mean | I32F32 Median | I32F32 P95 |
|---|---|---|---|---|---|---|
| sin | 6.06e-4 | 8.78e-5 | 1.28e-3 | 1.16e-8 | 1.68e-9 | 2.43e-8 |
| cos | 6.45e-4 | 9.03e-5 | 1.38e-3 | 1.22e-8 | 1.72e-9 | 2.64e-8 |
| tan | 7.20e-5 | 3.57e-5 | 2.20e-4 | 1.28e-9 | 3.98e-10 | 3.03e-9 |
| asin | 1.85e-4 | 3.60e-5 | 4.75e-4 | 4.49e-9 | 7.35e-10 | 8.89e-9 |
| acos | 2.33e-5 | 1.47e-5 | 6.86e-5 | 4.51e-10 | 2.71e-10 | 1.38e-9 |
| atan | 1.50e-5 | 1.23e-5 | 3.45e-5 | 3.01e-10 | 2.44e-10 | 7.05e-10 |
| sinh | 9.80e-5 | 6.23e-5 | 2.79e-4 | 1.52e-9 | 9.64e-10 | 4.29e-9 |
| cosh | 9.40e-5 | 5.75e-5 | 2.77e-4 | 1.44e-9 | 8.90e-10 | 4.25e-9 |
| tanh | 1.60e-5 | 1.32e-5 | 2.56e-5 | 2.25e-10 | 1.22e-10 | 3.90e-10 |
| coth | 6.68e-6 | 3.54e-6 | 1.80e-5 | 1.41e-10 | 1.16e-10 | 2.74e-10 |
| asinh | 6.44e-4 | 4.83e-4 | 1.75e-3 | 1.03e-8 | 7.59e-9 | 2.85e-8 |
| acosh | 6.74e-4 | 5.21e-4 | 1.80e-3 | 1.05e-8 | 7.96e-9 | 2.88e-8 |
| atanh | 3.01e-4 | 5.90e-5 | 6.25e-4 | 6.68e-9 | 1.32e-9 | 1.44e-8 |
| acoth | 2.10e-3 | 1.33e-3 | 6.67e-3 | 4.26e-8 | 2.62e-8 | 1.39e-7 |
| exp | 5.98e-3 | 1.47e-5 | 4.13e-2 | 9.49e-8 | 1.50e-9 | 6.50e-7 |
| ln | 1.35e-5 | 8.76e-6 | 2.97e-5 | 4.50e-10 | 3.48e-10 | 9.17e-10 |
| log2 | 1.33e-5 | 8.48e-6 | 2.92e-5 | 3.46e-10 | 2.24e-10 | 7.21e-10 |
| log10 | 1.44e-5 | 9.28e-6 | 3.14e-5 | 4.49e-10 | 3.27e-10 | 9.07e-10 |
| pow2 | 3.62e-4 | 2.24e-5 | 2.37e-3 | 5.64e-9 | 4.29e-10 | 3.67e-8 |
| sqrt | 1.77e-7 | 1.16e-7 | 4.74e-7 | 2.70e-12 | 1.78e-12 | 7.16e-12 |