Trait DecimalConsts

Source

pub trait DecimalConsts: Sized {
    // Required methods
    fn pi() -> Self;
    fn tau() -> Self;
    fn half_pi() -> Self;
    fn quarter_pi() -> Self;
    fn golden() -> Self;
    fn e() -> Self;
}

Expand description

Well-known mathematical constants available on every decimal width (D9 / D18 / D38 / D76 / D153 / D307).

Import this trait to call D38s12::pi(), D76::<35>::e(), etc.

All returned values are computed from a raw integer reference at the tier’s maximum storage precision (75 digits for D9/D18/D38 and D76; 153 for D153; 307 for D307) without passing through f64, then rescaled down to the caller’s SCALE with half-to-even rounding. The result is within 0.5 ULP of the canonical decimal expansion at every supported scale on every width.

The one situation where a method does not return a value is when the constant’s magnitude exceeds the type’s storage range at the caller’s SCALE — e.g. D38<38>::pi() would need 3.14 × 10³⁸, which exceeds i128::MAX ≈ 1.7×10³⁸. The method panics with a clear “constant out of storage range” message in that case.

Required Methods§

Source

fn pi() -> Self

Pi (~3.14159265…). One half-turn in radians.

Source: ISO 80000-2 / OEIS A000796. Rescaled per-tier (see the module-level table) to the caller’s SCALE via the crate-default rounding mode.

§Precision

N/A: constant value, no arithmetic performed.

Source

fn tau() -> Self

Tau (~6.28318530…). One full turn in radians.

Defined as 2 * pi. Rescaled per-tier (see the module-level table) to the caller’s SCALE via the crate-default rounding mode.

§Precision

N/A: constant value, no arithmetic performed.

Source

fn half_pi() -> Self

Half-pi (~1.57079632…). One quarter-turn in radians.

Defined as pi / 2. Rescaled per-tier (see the module-level table) to the caller’s SCALE via the crate-default rounding mode.

§Precision

N/A: constant value, no arithmetic performed.

Source

fn quarter_pi() -> Self

Quarter-pi (~0.78539816…). One eighth-turn in radians.

Defined as pi / 4. Rescaled per-tier (see the module-level table) to the caller’s SCALE via the crate-default rounding mode.

§Precision

N/A: constant value, no arithmetic performed.

Source

fn golden() -> Self

The golden ratio (~1.61803398…). Dimensionless.

Defined as (1 + sqrt(5)) / 2. Source: OEIS A001622. Rescaled per-tier (see the module-level table) to the caller’s SCALE via the crate-default rounding mode.