Function unscale_i_pair_masked 

pub fn unscale_i_pair_masked<P, V>(a: V, b: V, z: V, far: V::Mask) -> (V, V)
where
    V: FloatVector + TranscendentalMathWithPolicy,
    P: Policy,

unscale_i_pair with the far mask supplied, for an arithmetic where “far” is not a plain comparison: over C it is Re z >= threshold, and z itself is the exponent.