gcd and simp:false;



Richard,

Yes, we have talked about this, and despite my best efforts I still struggle to understand when something is "evaluated" and when something else is "simplified" in Maxima.

(%i1) simp:false$
(%i2) gcd(x,y);
(%o2) 1

(%i3) 1+1;
(%o3) 1+1

Of course everything has to be evaluated!  It just isn't clear to me when the simplifier is used and when it isn't.  I know the view "if you want simp:false then use something else" has been expressed before.  I can't argue with this.  But, we could replace this with "for all <expr>, if you want <expr> then use something else" which would also be true, but I'm not usually that nihilistic! 

:-)

C
________________________________________
From: Richard Fateman [fateman at eecs.berkeley.edu]
Sent: 25 January 2012 18:55
To: Chris Sangwin
Cc: maxima at math.utexas.edu
Subject: Re: [Maxima] gcd and simp:false;

On 1/25/2012 11:02 AM, Chris Sangwin wrote:
>
> I'm confused why the gcd function does not respect simp:false.
>
> (%i1) simp:false$
> (%i2) gcd(x,y);
> (%o2) 1
>
> Any suggestions?
> Chris
>
The gcd function is being evaluated, not simplified.
If you turn off evaluation also, you have converted your maxima system
into a brick.  In particular you could never turn evaluation
back on without evaluating something.


I think we've discussed this before, but simp:false
is almost always a bad idea.  If you don't want simplification,
maybe you should be using a different program.

RJF