Significant digits in a float?

[Steven D'Aprano]

On Tue, 29 Apr 2014 09:38:33 -0400, Roy Smith wrote:

> > What reason do you have to think that something recorded to 14 decimal
> > places was only intended to have been recorded to 4?
> 
> Because I understand the physical measurement these numbers represent.
> Sometimes, Steve, you have to assume that when somebody asks a question,
> they actually have asked the question then intended to ask.

Heh, having been in *exactly* your situation of having people questioning 
my constraints, I can sympathise with your frustration. I was pretty 
frustrated too.

But I've also been in situations where I've been so close to a question 
that I couldn't see the big picture, and a few dumb questions made me 
realise that in fact I was missing something obvious which changed the 
situation completely. To paraphrase:

Me:   How do I square the circle with only a compass and straightedge?
Them: You can't. It's impossible. Are you sure you need only use
      compass and straightedge? Can you use a rolling circle and a 
      marked ruler?
Me:   Come come, I've told you my requirements, compass and straightedge
      only. Now solve my problem!
Them: Does it have to be in Euclidean space? Why don't you perform 
      the construction in Gauss-Bolyai-Lobachevsky space?
Me:   Perhaps a rolling circle and ruler isn't such a bad idea...


http://www.cut-the-knot.org/impossible/sq_circle.shtml
http://mathworld.wolfram.com/CircleSquaring.html

:-)




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/