behavior of ind, = and equal, also fiddling with limit

What is the difference between indefinite and undefined in Maxima, do they mean the same thing?  

Google "indefinite and undefined"

You get from http://thesaurus.reference.com

      Main Entry: indefinite
      Part of Speech: adjective
      Definition: ambiguous, vague
      Synonyms: broad, confused, doubtful, dubious, equivocal,evasive, general, ill-defined, imprecise, indeterminable, 
indeterminate, indistinct, inexact, inexhaustible, infinite, innumerable,intangible, loose, obscure, shadowy, uncertain, unclear, 
undefined, undependable, undetermined, unfixed, unknown, unlimited,unsettled, unspecific, unsure, wide
      Antonyms: certain, definite, distinct, sure


      Main Entry: undefined
      Part of Speech: adjective1
      Definition: infinite
      Synonyms: boundless, endless, enduring, forever, limitless,perpetual, unending, vast
      Antonyms: bounded, finite, limited


      Main Entry: undefined
      Part of Speech: adjective2
      Definition: vague
      Synonyms: ambiguous, dim, fuzzy, hazy, indeterminate, muddy, obscure, unclear, unspecific
      Antonyms: clear, definite, sure



My 2 cents worth,

Rich




----- Original Message ----- 


From: "Richard Fateman" <fateman at cs.berkeley.edu>
To: "Stavros Macrakis" <macrakis at alum.mit.edu>
Cc: "Richard Fateman" <fateman at EECS.Berkeley.EDU>; "Maxima List" <maxima at math.utexas.edu>
Sent: Thursday, September 24, 2009 1:09 PM
Subject: Re: [Maxima] behavior of ind, = and equal, also fiddling with limit


Stavros Macrakis wrote:
> On Thu, Sep 24, 2009 at 11:45 AM, Richard Fateman
> <fateman at cs.berkeley.edu <mailto:fateman at cs.berkeley.edu>> wrote:
>
>     is (ind=ind)   returns true
>     is (equal(ind,ind)) returns false.
>
>
> I believe this is correct, though confusing.

I sort of agree,  except that the documentation says that is
(equal(a,b))  is computed by testing (0=ratsimp(a-b)).  And that would
result in true, not false.

The limit questions were really asking about ind  [for indefinite]  and
und [for undefined]. If we need both, are we handling them correctly?
{I think not.  (und-und -> 0,  ind-ind->0,  and for that matter, inf-inf
-> 0  in the simplifier)}

We also have, at least in some Lisps,  not-a-numbers ... NaNs -- single,
double, maybe extended, and there are actually a huge number
of distinguishable NaNs.
NaN is specified by a reserved exponent, but the fraction part can be
used to store info.

I'm still thinking about limit sets vs. intervals :)

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