Description: Definition of the auxiliary function inftyexpitau parameterizing the circle at infinity CCinfty in CCbar . We use coupling with { R. } to simplify the proof of bj-inftyexpitaudisj . (Contributed by BJ, 22-Jan-2023) The precise definition is irrelevant and should generally not be used. TODO: prove only the necessary lemmas to prove |- ( A e. RR /\ B e. RR ) -> ( ( inftyexpitauA ) = ( inftyexpitauB ) <-> ( A - B ) e. ZZ ) ) . (New usage is discouraged.)