Re: [Axiom-mail] Few questions about expressions...

[Francois Maltey]

A previous mail asks about :

> > expand(((-r1*r2*uoff)+((r2+r1)*r3+r1*r2)*ue)/(r2*r3));
>                            r1 uoff        ue r1   ue r1
>                          - ------- + ue + ----- + -----
>                              r3            r2      r3
> 

// A //

Has someone already tested an hold function for Expression as mupad had ?

So the expression 1+x + hold (1/(x-1)) remains as.
It's easy to eval/remove the hold form and then axiom gets x^2/(x-1).
And it's possible to have the reverse function partFrac.

Do you have any idea about it ?

This hold function allows expanded fractions, factorised Expression, 
<< partFrac >>, series in (x-a)^k, products of sum, and so.

// B //

What is the goal of AlgebraicNumber ?

Is it an algebraic domain in which 
  2^(1/2) = -2^(1/2) and sqrt(6*sqrt(5)+14) = - 3 - sqrt 5 
without any branch-cut.

Or is it a Complex domain near from RealClosure Fraction Integer in 
which axiom chooses the good branch : sqrt (%i*2) = + 1 + %i, 
not any other root.

// C // 

What is the goal of Expression ? 
to compute with an << algebraic point of view >> 
              or a << calculus point of view >> ?

A calculus point of view near of the other cas may be useful for my 
(and other) calculus for scientifics students.

Is it more effective to look arround Expression 
or to write an other domain Calculus, with duplicate parts of code ?

Thanks a lot for your points of view.

Francois