2. So, they hold for the Complex numbers as well. The gymnastics with complex sinh and cosh seems to be redundant. Well, I would be a little careful changing these. Some of the definitions in numerical part of the Prelude look more convoluted than they need to be, but it's because they have better numerical properties. I know Joe Fasel spent a lot of work on getting definitions that are numerically well behaved.

But we should definitely have the "default definitions" for sinh and cosh. Any decent implementation will of course override these for speed and accuracy. -- Lennart