[math-fun] fib(1/2)

Binet's and another formula give Sqrt[1/5 - (2 I)/5] and ((1 - I) (Cosh[ArcCsch[2]/2] + I Sinh[ArcCsch[2]/2]))/Sqrt[5] but FullSimplify can't get the former from the latter. But it agrees they're equal. --rwg