radcan not Idempotent



but

 (%i391) ((-x-1)^(-bb-aa-2)*(x+2)^aa)/(((x+2)/(x+1))^aa*(1/(x+1)-(x+2)/(x
 +1)^2)*(1-(x+2)/(x+1))^bb);
 (%o391) ((-x-1)^(-bb-aa-2)*(x+2)^aa)/(((x+2)/(x+1))^aa*(1/(x+1)-(x+2)/(x
 +1)^2)*(1-(x+2)/(x+1))^bb)

 (%i392) radcan(%);
 (%o392) -(x+1)^aa/(-x-1)^aa

radcan(%-radcan(%)); /* gives zero */
> 0

which is all that the documentation guarantees will work.  I rely on this to tell if an expression is linear or quadratic by 
subtraction of the radcan'ed expression from its simplified result.  I hope that still works.

Rich

----- Original Message ----- 
From: "Richard Fateman" <fateman at cs.berkeley.edu>
To: "Barton Willis" <willisb at unk.edu>; "Maxima List" <maxima at math.utexas.edu>
Sent: Sunday, June 28, 2009 8:58 PM
Subject: Re: [Maxima] radcan not Idempotent


Barton Willis wrote:
> Here is an expression e for which radcan(radcan(e)) # radcan(e). I'd
> call this a bug:
>
> (%i391) ((-x-1)^(-bb-aa-2)*(x+2)^aa)/(((x+2)/(x+1))^aa*(1/(x+1)-(x+2)/(x
> +1)^2)*(1-(x+2)/(x+1))^bb);
> (%o391) ((-x-1)^(-bb-aa-2)*(x+2)^aa)/(((x+2)/(x+1))^aa*(1/(x+1)-(x+2)/(x
> +1)^2)*(1-(x+2)/(x+1))^bb)
>
> (%i392) radcan(%);
> (%o392) -(x+1)^aa/(-x-1)^aa
>
> (%i393) radcan(%);
> (%o393) -1/(-1)^aa
>
>
> Barton
>
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> Maxima at math.utexas.edu
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>
for what it is worth, commercial macsyma gets 2 different answers, but
the second one is
 - (%e)^( - %i * %pi * aa)

its a bug, I think.
RJF

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