libm 0.2.15

libm in pure Rust
Documentation 
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/// Absolute value (magnitude) (f128)
///
/// Calculates the absolute value (magnitude) of the argument `x`,
/// by direct manipulation of the bit representation of `x`.
#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
pub fn fabsf128(x: f128) -> f128 {
    super::generic::fabs(x)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn sanity_check() {
        assert_eq!(fabsf128(-1.0), 1.0);
        assert_eq!(fabsf128(2.8), 2.8);
    }

    /// The spec: https://en.cppreference.com/w/cpp/numeric/math/fabs
    #[test]
    fn spec_tests() {
        assert!(fabsf128(f128::NAN).is_nan());
        for f in [0.0, -0.0].iter().copied() {
            assert_eq!(fabsf128(f), 0.0);
        }
        for f in [f128::INFINITY, f128::NEG_INFINITY].iter().copied() {
            assert_eq!(fabsf128(f), f128::INFINITY);
        }
    }
}