nalgebra::assert_approx_eq_ulps!

macro_rules! assert_approx_eq_ulps(
    ($given: expr, $expected: expr, $ulps: expr) => ({
        let ulps = $ulps;
        let (given_val, expected_val) = (&($given), &($expected));
        if !ApproxEq::approx_eq_ulps(given_val, expected_val, ulps) {
            panic!("assertion failed: `left ≈ right` (left: `{:?}`, right: `{:?}`, tolerance: `{:?}`)",
                *given_val, *expected_val, ulps
            )
        }
    })
);

Asserts approximate equality within a given tolerance of two values with the ApproxEq trait, with tolerance specified in ULPs.