[Axiom-developer] Bug: using exp as a symbol in ** (was: System error: Cannot take first of an empty list

[William Sit]

The error apparently comes from EXPR where the implementation is
  x**y == exp(y * log(x))

so exp^log(x) is computed as
 
  exp(log(x) * log(exp))

which should be ok, but then the system handles log exp and tries to simplify it
to the identity map, and not finding the argument.

William
---

> 
> Simpler:
> 
> (1) -> exp^3
> 
>            3
>    (1)  exp
>                                    Type: Polynomial Integer
> (2) -> a^log(x)
> 
>          log(x)
>    (2)  a
>                                    Type: Expression Integer
> (3) -> exp^log(x)
> 
>    >> System error:
>    Cannot take first of an empty list
> 
> protected-symbol-warn called with (NIL)
>