Bill McCarthy wrote:
> On Sun 22-Jun-08 2:49pm -0600, Tony Mechelynck wrote:
>
> > On 21/06/08 13:56, Bram Moolenaar wrote:
>
> >> Ben Schmidt wrote:
>
> >>> - Furthermore, on investigation, it seems there is an interesting
> >>> definition of 'significant figures' in the library docs, and %.15g =
> is
> >>> the correct value, not %.16g. It might be worth noting at the print=
> f()
> >>> docs, or the Float docs where precision is mentioned, or both, that
> >>> maximum precision output can be obtained with %.15g.
> >>
> >> I don't see this, for me %.16g does produce a longer result.
> > [...]
> >
> > A higher number prints additional digits, but starting at some point,
> > the additional digits are bogus. Example:
> >
> > :echo printf('%.25g', 1.0/3.0)
> > 0.3333333333333333148296163
> >
> > Anything after the row of threes is bogus.
> >
> > :echo printf('%.25g', 10.0/9.0)
> > 1.1111111111111111604543567
> >
> > Here anything after the ones is bogus. And so on. These examples seem to
> > imply that, in these cases at least, %.16g is the maximum valid precision.
>
> Yes, the only way to have as many as, say, 15 significant
> digits but as few as possible more than 1 is to use a
> function:
>
> Bram, I would like to see something like this representation
> be the default for :echo float_expression.
>
> ==========================================
> " Do a printf with %g printing as many as 15 significant
> " digits but as few as possible more than 1.
>
> function! PG(x)
> let x = a:x + 0.0
> let y = x < 0 ? -x : x " No fabs() in official release
> let n = x == 0.0 ? 0 : float2nr(floor(log10(y)))+1
>
> if n < -1 || n > 15
> return substitute(substitute(printf("%0.14e",x),
> \'\.\=0*e','e',''),'\([eE][+-]\)0*\([0-9]\+\)','\1\2','')
> else
> return substitute(substitute(printf("%0.*f", 15-n, x),
> \'\([^.]*\..\{-}\)0\+$','\1',''),'\.$','','')
> endif
> endfunction
> ==========================================
>
> Examples:
>
> :echo PG(0.012)
> 0.012
> :echo PG(-0.00123)
> -1.23e-3
> :echo PG(7/4.0)
> 1.75
> :echo PG(123456789012345.0)
> 123456789012345
> :echo PG(1.0e20)
> 1e+20
I get the feeling we are splitting hairs here. Anyway, current Vim does
like the above. Except:
:echo PG(-0.00123)
-1.23e-3
I would prefer to see -0.00123, as Vim does now.
:echo PG(123456789012345.0)
123456789012345
I can't read what the order of that number is, 1.234568e14 is just as
good. Matter of taste, I suppose.
--
hundred-and-one symptoms of being an internet addict:
84. Books in your bookcase bear the names Bongo, WinSock and Inside OLE
/// Bram Moolenaar -- [EMAIL PROTECTED] -- http://www.Moolenaar.net \\\
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\\\ download, build and distribute -- http://www.A-A-P.org ///
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