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## Re: [Axiom-developer] bug in complexNormalize?

 From: Waldek Hebisch Subject: Re: [Axiom-developer] bug in complexNormalize? Date: Sun, 27 Apr 2008 20:01:38 +0200 (CEST)

> Any help on this would really be appreciated.
> Is it really a bug in complexNormalize?
>
> --S 5 of 14
> aa:=integrate(sinh(a*x)^2*cosh(a*x)^2,x)
> --R
> --R
> --R                          3            3
> --R        cosh(a x)sinh(a x)  + cosh(a x) sinh(a x) - a x
> --R   (1)  -----------------------------------------------
> --R                               8a
> --R                                          Type: Union(Expression
> Integer,...)
> --E
>
> --S
> bb:=sinh(4*a*x)/(32*a)-x/8
>
>         sinh(4a x) - 4a x
>    (2)  -----------------
>                32a
>                                                      Type: Expression Integer
> --E
>
> --S
> cc:=complexNormalize(aa-bb)
>
>    (3)  0
>                                                      Type: Expression Integer
> --E
> @
> {\bf NOTE}, that if we compute this same'' expression directly
> we get a different answer. This appears to be a bug.
> --S
> dd:=complexNormalize(integrate(sinh(a*x)^2*cosh(a*x)^2,x)-sinh(4*a*x)/(32*a)-x/8)
>
>           x
>    (4)  - -
>           4
>                                                      Type: Expression Integer
> --E
> @
>

I get:

complexNormalize(integrate(sinh(a*x)^2*cosh(a*x)^2,x)-(sinh(4*a*x)/(32*a)-x/8))

(5)  0
Type: Expression Integer

AFAICS the 'dd' expression lacks parentheses around copy of 'bb' term,
so you get 'x/8' with different sign.

--
Waldek Hebisch
address@hidden



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