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[sage-support] Re: Simplification Issue Implicates Canonical Form Mark Rahner Sat Feb 18 20:00:12 2012

I appreciate that background info.  I hadn't tried invoking maxima
because I read somewhere that simplify() used maxima.  I must've been
reading outdated material.  As you stated, maxima does the correct
thing.  Because Sage can invoke maxima, perhaps I have a work around.
You're right that this issue should be considered in the context of
powers.  In that context, I think it is even more clear that
"5^(-1/2)" is simpler than "(1/5) * 5^(1/2)".  Leaving the additional
term doesn't seem like a big deal, but by preventing subsequent
simplifications, and by combining and recombining with other large
expressions, it can have highly undesirable effects.
I took a quick look at ginsh, the GiNaC interactive shell.  It
converts 1/sqrt(5) to 1/5*sqrt(5) so I suspect that this issue can be
traced to the GiNaC canonical form.  I'm not a CAS expert but I know a
fair amount about computer system interfaces and I'm sure this issue
adversely impacts the user experience.  Nobody would select equation
obfuscation mode given the choice.
I think this issue should be taken up with the GiNaC folks.  Do they
hang out in this group?
-Mark

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