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[Axiom-math] expand
From: |
root |
Subject: |
[Axiom-math] expand |
Date: |
Mon, 17 Nov 2003 18:25:00 -0500 |
Richy,
> But, just tell me one thing, please. Is this a bug or need I read the
> book in order to understand?
>
> (1) -> expand((x+y+z)^2-x^2-y^2-z^2)
>
> [Loading stuff, lines deleted]
>
> (1) (2y + 2x)z + 2x y
>
> Type: Polynomial Integer
> (2) -> expand(expand(expand((x+y+z)^2-x^2-y^2-z^2)))
>
> (2) (2y + 2x)z + 2x y
> Type: Polynomial Integer
>
>
> Hmm, not if you use some really funny definition of "to expand". I would
> rather have expected something like 2x z + 2y z + 2x y. ?!?
(1) -> a:=(x+y+z)^2-x^2-y^2-z^2
(1) (2y + 2x)z + 2x y
Type: Polynomial Integer
(2) -> c:DMP([x,y,z],FRAC(INT)):=a
(2) 2x y + 2x z + 2y z
Type: DistributedMultivariatePolynomial([x,y,z],Fraction Integer)
The issue is the type chosen. The result (1) is a polynomial in z of the
form a * z + b where a == (2y + 2x) and b == 2xy
If you want x and y to also be variables you need the second form where
you explicitly request that x, y, and z are variable.
The display of an equation is intimately bound to its type.
Tim
- [Axiom-math] expand,
root <=