Changes http://page.axiom-developer.org/zope/mathaction/AxiomMail/diff -- Martin Rubey wrote:
>Dear Doug, > >there are two issues in your code: > > >Doug Stewart writes: > > > >>)clear all >>digits 20 >>-- n:=x^3+a1*x^2+a2*x+a3 ::Polynomial Fraction Integer >> >>Q:=(3*a2-a1^2)/9 >>R:=(9*a1*a2-27*a3-2*a1^3)/54 >>S:=(R+(Q^3+R^2)^(1/2))^(1/3) >>T:=(R-(Q^3+R^2)^(1/2))^(1/3) >>x1:=S+T-a1/3 >> >> > >note that x1 is *not* a polynomial. Not even a rational function. > > > > But it is a constant ---- How can I tell axiom that it is a constant? I tried this way but :-( )clear all digits 20 -- n:=x^3+a1*x^2+a2*x+a3 ::Polynomial Fraction Integer a1:=1 a2:=1 a3:=1 Q:=(3*'a2-'a1^2)/9 R:=(9*'a1*'a2-27*'a3-2*'a1^3)/54 S: Complex Float :=(R+(Q^3+R^2)^(1/2))^(1/3) I thought that if I gave a1 a2 a3 some in integer values, that Maxima would then know that it was a constant but no it thinks it is a variable???? >However, if you *can* avoid this domain (often you can't), try to do so, since >it has a major drawback: > >A computer cannot test reliably whether some element of Expression Integer is >zero or not. Axiom tries, but often fails. For example, the first example above >is not zero for Axiom... > >(MuPAD, Mathematica and Maple try harder, but they often fail, too) > >Note that this problem does not arise for many other domains: you can test for >zero in > >Integer, >Polynomial Integer, >AlgebraicNumber, >PrimeField 5 >Matrix Integer, >Fraction Polynomial PrimeField 1783 > >and so on. > >Martin > > > > Thanks for your help, It clarified what I was seeing. --- a big mess of numbers that was realy zero. Doug Stewart _______________________________________________ Axiom-mail mailing list Axiom-mail@nongnu.org http://lists.nongnu.org/mailman/listinfo/axiom-mail -- forwarded from http://page.axiom-developer.org/zope/mathaction/[EMAIL PROTECTED] _______________________________________________ Axiom-developer mailing list Axiom-developer@nongnu.org http://lists.nongnu.org/mailman/listinfo/axiom-developer
