Re: Another newbie question

[WJ Atsma]

Ola

Number of decimal places and precision are not necessarily related, at 
least not
on a computer. The relationship you learn in math and physics (round 
off to
the number of significant digits + 1) is of no concern to the computer. 
Matlab and
excel have the same limitation. The programmer's choice to show zeros 
rather than
the imprecise results from round-off errors after an operation may be 
nice for the
intuitive user, but don't really provide information. For example, 
1.000000 +/- 0.2
is just as accurate as 1.00233748 +/- 0.2. The round-off provides 
useful information
sometimes even.

Not to say that something useful couldn't be done. It should be 
possible to pass
numbers with a precision qualifier and propagate it through your 
equations, but
nobody has done this and I don't know of any other numerical 
packages/spreadsheets
that do.

Happy computing,

Willem


On 2003.08.01 02:02 Fausto Arinos de A. Barbuto wrote:
> On Thu, 2003-07-31 at 10:58, John W. Eaton wrote:
>
> > | Take Excel as an example. One can increase
> > | the floating point representation of any real number by as many
> > | decimal places as he/she wants. However, only zeroes are shown
> > | from the 14th decimal place on. It also marvels me that a much-
> > | less-than-professional program such as Windows Calculator can
> > | represent real numbers with 31 exact decimal places -- and Octave
> > | can't.
> >
> > If you are trolling, find another venue.  If you have a real



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