Re: [xslt] number() floated?

[Vincent Lefevre <vincent+gnome vinc17 org>]

On 2012-01-03 23:00:16 +0100, Vincent Lefevre wrote:
> On 2012-01-03 20:53:40 +0000, Laurence Rowe wrote:
> > On 16 December 2011 17:06, Konrad Korzeniowski <konrad pandur net> wrote:
[...]
> > >     <xsl:value-of select="number('8.95')"/>
[...]
> 
> Except that this seems to be a bug here:

After looking at the spec, I confirm this is a bug. The XPath spec
says for number(): "a string that consists of optional whitespace
followed by an optional minus sign followed by a Number followed
by whitespace is converted to the IEEE 754 number that is nearest
(according to the IEEE 754 round-to-nearest rule) to the mathematical
value represented by the string"

The nearest value X is the following one (represented exactly in
radix 16, thanks to %a):

> $ /usr/bin/printf "%a\n" 8.95
> 0x8.f33333333333333p+0

But actually (see below) the internal representation doesn't matter
here.

Concerning xsl:value-of, the XSLT spec says that for a number, the
XPath string() fucntion is used, and the XPath spec says for the
above value: "otherwise, the number is represented in decimal form
as a Number including [...]; beyond the one required digit after
the decimal point there must be as many, but only as many, more
digits as are needed to uniquely distinguish the number from all
other IEEE 754 numeric values." (FYI, that's the IEEE 754 rule for
conversions.)

As a consequence, the output value should be "8.95" (like the input)
because 8.95 rounds to X and has less than 17 digits.

-- 
Vincent Lefèvre <vincent vinc17 net> - Web: <http://www.vinc17.net/>
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