Rational enclosures for inverse hyperbolic functions #
These enclosures compose square roots, logarithms, and exact interval arithmetic.
Inverse hyperbolic cosine accepts inputs at least one; inverse hyperbolic tangent requires
an interval strictly inside (-1, 1). Inverse hyperbolic sine uses monotonicity and odd symmetry
to avoid cancellation in its logarithmic formula at negative inputs.
InverseHyperbolicProof proves containment for every real member of an accepted interval.