I believe real constant $C$ is irrational iff its continued fraction is infinite. There are many famous constants which irrationality is unknown. For a lot of constants sage gives exception: ``` sage: cf=list(continued_fraction(catalan)) ValueError: the length is infinite! ```
Should the error use weaker wording? Another test is coercing to QQ and there the wording is better: ``` sage: QQ(catalan) TypeError: unable to convert catalan to a rational -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/sage-devel/CAGUWgD-OVzQJ9ZFsZU3Mz3kZgKCzSiM%2BWn-y%2B_vAGP%3D6D2ugNQ%40mail.gmail.com.
