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 printf()
>>> 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
--
Best regards,
Bill
--~--~---------~--~----~------------~-------~--~----~
You received this message from the "vim_dev" maillist.
For more information, visit http://www.vim.org/maillist.php
-~----------~----~----~----~------~----~------~--~---
