error - system too complex



I haven't  been following this, since I've been on
vacation,
but the claim that a system uses IEEE floats for
representation
is a far cry from actually supporting the
operations.  A system that
always provokes an error on division by zero instead
of producing
an infinity    is NOT conforming to IEEE operations.

RJF

----- Original Message -----
From: Raymond Toy 
Date: Thursday, June 23, 2005 9:52 am
Subject: Re: [Maxima] error - system too complex

> >>>>> "Robert" == Robert Dodier
 writes:
> 
>    Robert> --- Nikodemus Siivola
 wrote:
>    >> Indeed, ANSI CL specifies
:IEEE-FLOATING-POINT in *FEATURES* to
>    >> indicate that the implementation purports to
conform to the
>    >> requirements of IEEE Standard for Binary
Floating-Point 
> Arithmetic.    >> However, how what this exactly
means is rather 
> vague.
>    Robert> I find CMUCL and GCL both have
:IEEE-FLOATING-POINT in
>    Robert> *FEATURES*, although they both barf on
computations which
>    Robert> would yield not-a-number or infinity.
Clisp is honest 
> enough
> If you have an example of this barfing, please
show it.  By default,
> in CMUCL, things that would produce NaN or
infinity signal errors.
> But you can change that so it does return NaN or
infinity.  Of course,
> all computations after that are likely to be
useless.  And it's likely
> maxima doesn't know what to do with NaN or infinity.
> 
>    Robert> Maxima probably should try to work
around the underlying
>    Robert> Lisp's prohibition of special values.
> 
> Which special values?  NaN and infinity?  CMUCL
handles them fine.
> 
> Ray
> 
> 
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