Significant figures calculation

[Mel]

Erik Max Francis wrote:

> Mel wrote:
>> Erik Max Francis wrote:
>> 
>>> Chris Angelico wrote:
>>>> On Tue, Jun 28, 2011 at 12:56 PM, Steven D'Aprano
>>>> <steve+comp.lang.python at pearwood.info> wrote:
>>>>> Zero sig figure: 0
>>> That's not really zero significant figures; without further
>>> qualification, it's one.
>>>
>>>> Is 0.0 one sig fig or two?
>>> Two.
>>>
>>>> (Just vaguely curious. Also curious as to
>>>> whether a zero sig figures value is ever useful.)
>>> Yes.  They're order of magnitude estimates.  1 x 10^6 has one
>>> significant figure.  10^6 has zero.
>> 
>> By convention, nobody ever talks about 1 x 9.97^6 .
> 
> Not sure what the relevance is, since nobody had mentioned any such thing.
> 
> If it was intended as a gag, I don't catch the reference.

I get giddy once in a while.. push things to limits.  It doesn't really mean 
anything.  The point was that it's only the 2 in a number like 2e6 that is 
taken to have error bars.  The 6 is always an absolute number.  As is the 10 
in 2*10**6.  The thought also crossed my mind of a kind of continued 
fraction in reverse -- 2e1.3e.7 .  I managed to keep quiet about that one.

	Mel.