rust/src/libstd/cmp.rs

#[forbid(deprecated_mode)];
#[forbid(deprecated_pattern)];
/// Additional general-purpose comparison functionality.

const fuzzy_epsilon: float = 1.0e-6;

trait FuzzyEq {
    pure fn fuzzy_eq(other: &self) -> bool;
}

impl float: FuzzyEq {
    pure fn fuzzy_eq(other: &float) -> bool {
        return float::abs(self - *other) < fuzzy_epsilon;
    }
}

impl f32: FuzzyEq {
    pure fn fuzzy_eq(other: &f32) -> bool {
        return f32::abs(self - *other) < (fuzzy_epsilon as f32);
    }
}

impl f64: FuzzyEq {
    pure fn fuzzy_eq(other: &f64) -> bool {
        return f64::abs(self - *other) < (fuzzy_epsilon as f64);
    }
}

#[test]
fn test_fuzzy_equals() {
    assert ((&1.0).fuzzy_eq(&1.0));
    assert ((&1.0f32).fuzzy_eq(&1.0f32));
    assert ((&1.0f64).fuzzy_eq(&1.0f64));
}