float-equality-without-abs

Require an absolute difference in Number.EPSILON comparisons

left - right < Number.EPSILON accepts every negative difference, including values that are arbitrarily far apart.
Instead, you SHOULD compare the absolute difference: (left - right).abs() < Number.EPSILON.

The absolute value is unnecessary only when left >= right is a proven invariant.

- Category: correctness
- Level: warning
- Fix: suggestion
- Scope: module

Reported

function approximatelyEqual(left: float64, right: float64): boolean {
    return left - right < Number.EPSILON;
}
Accepted

function approximatelyEqual(left: float64, right: float64): boolean {
    return (left - right).abs() < Number.EPSILON;
}
Prior art

- Clippy · floatequalitywithoutabs

language/linter/src/rules/correctness/floatequalitywithoutabs.rs:8