3.2*2 is 9.6 ... or maybe it isn't?

[Robert Kern]

On 2009-06-25 18:43, Scott David Daniels wrote:
> Robert Kern wrote:
>> ... I wish people would stop representing decimal floating point
>> arithmetic as "more accurate" than binary floating point arithmetic.
>> It isn't. Decimal floating point arithmetic does have an extremely
>> useful niche: ...
> Well, we don't actually have an arbitrary-precision, huge exponent
> version of binary floating point. In that sense the Decimal floating
> point beats it.

And while that's true, to a point, that isn't what Michael or the many others 
are referring to when they claim that decimal is more accurate (without any 
qualifiers). They are misunderstanding the causes and limitations of the example 
"3.2 * 3 == 9.6". You can see a great example of this in the comparison between 
new Cobra language and Python:

   http://cobra-language.com/docs/python/

In that case, they have a fixed-precision decimal float from the underlying .NET 
runtime but still making the claim that it is more accurate arithmetic. While 
you may make (completely correct) claims that decimal.Decimal can be more 
accurate because of its arbitrary precision capabilities, this is not the claim 
others are making or the one I am arguing against.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco