Enum Scale 

pub enum Scale {
    Linear,
    Decibel(Decibel),
    Ratio {
        factor: f64,
    },
}

What a column of numbers means: base units, decibels against a reference, or a bare decibel difference.

A ratio is what a subtraction of two decibel columns leaves — a margin against a limit, say — and it has no reference, so it can never be converted back to base units. Keeping that in the type is what stops a margin from being read as a measurement.

Variants

Linear

Base units, as measured.

Decibel(Decibel)

Decibels against the stated reference.

Ratio

A decibel difference, carrying only the factor it was taken at.

Fields

factor: f64

The log factor the difference was taken at.

Implementations

impl Scale

pub fn factor(&self) -> Option<f64>

The log factor, if this scale is logarithmic at all.

pub fn reference(&self) -> Option<f64>

The reference, if this scale has one to convert against.

pub fn is_compatible(&self, other: &Self) -> bool

Whether values in these two scales may be combined at all.

pub fn sum(&self, other: &Self) -> Option<Self>

The scale a sum of these two lands in, when the sum means anything.

Adding a ratio back to a measurement restores the measurement’s scale — a margin added to a limit is a level again.

pub fn difference(&self, other: &Self) -> Option<Self>

The scale a difference of these two lands in, when it means anything.

Two levels differ by a ratio, and the references cancel: that is the margin calculation, and why Scale::Ratio exists.

Trait Implementations

impl Clone for Scale

fn clone(&self) -> Scale

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Scale

impl Debug for Scale

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Scale

fn default() -> Scale

Returns the “default value” for a type.

impl PartialEq for Scale

fn eq(&self, other: &Scale) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Scale