Trait gramit::fp::ApproxEq

pub trait ApproxEq<T = Self> {
    fn approx_eq(self, rhs: T) -> bool;
    fn within_threshold(self, rhs: T, threshold: T) -> bool;
}

Trait for types that can be compared for approximate equality.

Round-off error is a pervasive problem for floating-point arithemtic. Limited precision means that many expressions that are mathematically equal evaluate as unqual when computed using floating-point. A simple workaround is to, instead of comparing for exact equality, test whether values are within some small absolute difference of each other. The ApproxEq trait is intended to make this pattern a little more ergonomic by supplying a default difference threshold and encapsulating the comparison in a single method.

gramit implements ApproxEq for f32 and all of the gramit mathematical objects (vectors, matrices, etc). All of these implementations use the default threshold EQ_THRESHOLD_F32. There are also assertion macros assert_approx_eq and assert_within_threshold corresponding to ApproxEq's trait methods.

Required methods

fn approx_eq(self, rhs: T) -> bool

Compare two values for approximate equality, using a default difference treshold.

fn within_threshold(self, rhs: T, threshold: T) -> bool

Compare two values for approximate equality, using a user-defined difference threshold.

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Implementations on Foreign Types

impl ApproxEq<f32> for f32

fn approx_eq(self, rhs: f32) -> bool

fn within_threshold(self, rhs: f32, threshold: f32) -> bool

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Implementors

impl ApproxEq<Angle> for Angle

fn approx_eq(self, rhs: Angle) -> bool

fn within_threshold(self, rhs: Angle, threshold: Angle) -> bool

impl ApproxEq<Fraction> for Fraction

fn approx_eq(self, rhs: Self) -> bool

fn within_threshold(self, rhs: Self, threshold: Self) -> bool

impl ApproxEq<Mat2> for Mat2

fn approx_eq(self, rhs: Mat2) -> bool

fn within_threshold(self, rhs: Mat2, threshold: Mat2) -> bool

Compare two matrices for approximate equality, using a third matrix for component-wise thresholds.

impl ApproxEq<Mat3> for Mat3

fn approx_eq(self, rhs: Mat3) -> bool

fn within_threshold(self, rhs: Mat3, threshold: Mat3) -> bool

Compare two matrices for approximate equality, using a third matrix for component-wise thresholds.

impl ApproxEq<Mat4> for Mat4

fn approx_eq(self, rhs: Mat4) -> bool

fn within_threshold(self, rhs: Mat4, threshold: Mat4) -> bool

Compare two matrices for approximate equality, using a third matrix for component-wise thresholds.

impl ApproxEq<Quaternion> for Quaternion

fn approx_eq(self, rhs: Quaternion) -> bool

fn within_threshold(self, rhs: Quaternion, threshold: Quaternion) -> bool

Compare two Quaternions for approximate equality.

Uses a third Quaternion for element-wise thresholds.

impl ApproxEq<Vec2> for Vec2

fn approx_eq(self, rhs: Vec2) -> bool

fn within_threshold(self, rhs: Vec2, threshold: Vec2) -> bool

Compare two vectors for approximate equality.

Uses a third vector for component-wise thresholds.

impl ApproxEq<Vec3> for Vec3

fn approx_eq(self, rhs: Vec3) -> bool

fn within_threshold(self, rhs: Vec3, threshold: Vec3) -> bool

Compare two vectors for approximate equality.

Uses a third vector for component-wise thresholds.

impl ApproxEq<Vec4> for Vec4

fn approx_eq(self, rhs: Vec4) -> bool

fn within_threshold(self, rhs: Vec4, threshold: Vec4) -> bool

Compare two vectors for approximate equality.

Uses a third vector for component-wise thresholds.

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