On 24 May 2007 20:09:32 +0200 Martin Rubey replied to: Sumant S.R. Oemrawsingh who wrote:

 I just find this very strange:

 (1) -> %e

    (1)  %e
                                                      Type: Expression Integer
 (2) -> %pi

    (2)  %pi
                                                                      Type: Pi

 Why is %e of type Expression Integer, while %pi is of type Pi? Is there some
 deeper reason why Pi is its own type?

For some reasons, the original developers of axiom found %pi more important than %e. For elements of Expression Integer there is no direct conversion to Float, so they created an own domain HackPi?, which contains only %pi and the necessary conversion functions. The didn't want to do the same thing with %e though:

 (2) -> %e::Float

   Cannot convert from type Expression Integer to Float for value
   %e

In my opinion, we should have a domain for "general" constants, i.e., like Expression Integer but without variables, and, more generally, a domain for expressions with a given set of variables, similar to MPOLY. But I guess, that's a fair bit of work.