Steven D'Aprano wrote:
On Tue, 28 Jun 2011 06:53 am Ethan Furman wrote:
Harold wrote:
[...]
Empirical('1200.').significance
2
Well, that's completely wrong. It should be 4.
Empirical('1200.0').significance
5
What about when 1200 is actually 4 significant digits? Or 3?
Then you shouldn't write it as 1200.0. By definition, zeros on the right are
significant. If you don't want zeroes on the right to count, you have to
not show them.
Five sig figures: 1200.0
Four sig figures: 1200
Three sig figures: 1.20e3
Two sig figures: 1.2e3
One sig figure: 1e3
Zero sig figure: 0
That last one is not true; 0 is a one-significant figure estimate, and
represents a value between -0.5 and 0.5. (It's true that zeroes to the
left are never significant, but not when there's nothing in the figure
but zeroes.)
A zero-significant figure would be an order of magnitude estimate only.
These aren't usually done in the "e" scientific notation, but it would
be something like 10^3 (if we assume ^ is exponentiation, not the Python
operator).
c^2 is 9 x 10^16 m^2/s^2 to one significant figure. It's 10^17 m^2/s^2
to zero (order of magnitude estimate).
--
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