On Wed, May 09, 2007 at 18:12:56 -0400, Roberto C. Sánchez wrote:
> On Wed, May 09, 2007 at 10:29:55PM +0200, Florian Kulzer wrote:
> >
> > $ wcalc 10*pi
> > = 31.4159
> >
> > The god from the bible can create the universe, but he cannot round to
> > the nearest integer correctly? Did Brahma, Vishnu and Shiva have to help
> > him with the delicate balance of the natural constants?
> >
> You clearly don't understand the concept of significant digits.
Actually I understand the concept well enough to know that it cannot be
applied stringently if one deals with numbers that are divisible by
positive integer powers of ten and which are written down as words.
Obviously, "ten" and "thirty" fall into this category. Even if you write
"30" it is not really clear if you know this value to one or two
significant digits. Sometimes people claim that "30" by convention is
one significant digit and that you have to write "30." to indicate two
significant digits, but this is, as far as I know, not generally
accepted in the scientific community. (Scientists and engineers mostly
use semi-logarithmic notation anyway, which avoids these ambiguities.)
Furthermore, if you want to start patronizing other people about the
concept of significant digits then you should probably be more careful
yourself not to make statements which could be misconstrued as mix-ups
between "significant digits" and "decimals": In your earlier mail you
first give the "one significant digit" argument and then you abruptly
and without necessity switch to numbers that have three (5.00) or four
(10.00 and 30.00) significant digits. Everything you say is technically
correct[1] and it is maybe just a coincidence that these numbers have two
decimals, but at the very least this is unnecessarily confusing. What is
so special about four significant digits when two significant digits are
in fact the threshold for putting "ten" times pi out of range for
"thirty"?
[1] You avoided stating how many significant digits these numbers have
in your opinion and, maybe by pure luck, you chose a formulation
which left you enough wiggle room to use more significant digits
than strictly necessary. Being vague enough so as not to be wrong is
not the best way to demonstrate your understanding of a concept,
though.
--
Regards, | http://users.icfo.es/Florian.Kulzer
Florian |
