[Axiom-mail] integrate the PDF of normal distribution

[ming lu]

Hi group,
What is the prpper way to integrate the PDF of normal distribution?
I tried:
(4) -> 
integrate(x/(sigma*sqrt(2*%pi))*exp(-(x-mu)**2/(2*sigma**2)),x=%minusInfinity..%plusInfinity)
(4) ->
  (4)  "failed"
                                               Type: Union(fail: failed,...)
But if I give a value to sigma, then it works:

(9) -> sigma:=10
(9) ->
  (9)  10
(11) -> 
integrate(x/(sigma*sqrt(2*%pi))*exp(-(x-mu)**2/(2*sigma**2)),x=%minusInfinity..%plusInfinity)
(11) ->
             +---+
         2mu\|%pi
  (11)  -----------
         +-+ +----+
        \|2 \|2%pi
                   Type: Union(f1: OrderedCompletion Expression Integer,...)

Is it possible for axiom to work without specify a value to sigma?
Thanks,
Ming