RE: [xsl] negative double, very small absolute value: strange string conversion

["Michael Kay" <mike@xxxxxxxxxxxx>]

Looks like a bug. Saxon handles double-to-string conversion for common
values itself, but for very small values it delegates the job to Java
(simply to save coding effort for a complex but rare case), and it looks as
if Java and Saxon are both adding the minus sign.

Regards,

Michael Kay
http://www.saxonica.com/
http://twitter.com/michaelhkay 

> -----Original Message-----
> From: Wolfgang Laun [mailto:wolfgang.laun@xxxxxxxxx] 
> Sent: 18 March 2010 12:24
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: [xsl] negative double, very small absolute value: 
> strange string conversion
> 
> Just playing with double arithmetic (xsl is below), I notice 
> that the end of the output of this artless stylesheet is this:
> ...
> -9.556619453472961E-299
> -9.332636185032189E-302
> -9.113902524445497E-305
> -8.900295434028806E-308
> --8.6916947597938E-311
> --8.4879831639E-314
> --8.289046E-317
> --8.0948E-320
> --7.9E-323
> -0
> -0
> ...
> 
> So why are there double '-' in front of the last few values != -0 ?
> 
> $ java -version
> java version "1.6.0_0"
> OpenJDK Runtime Environment (IcedTea6 1.4.1) 
> (6b14-1.4.1-0ubuntu12) OpenJDK Server VM (build 14.0-b08, mixed mode)
> 
> java -cp /extra/saxon/saxon9he.jar net.sf.saxon.Transform 
> -it:iter -xsl:foo.xsl count=120 start=-1.0
> 
> <?xml version="1.0"?><!--foo.xsl-->
> <xsl:stylesheet version="2.0"
>     xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
>     xmlns:xs="http://www.w3.org/2001/XMLSchema";
>     xmlns:wl="wolfgang.laun">
> 
> <xsl:param name="start" as="xs:double"/> <xsl:param 
> name="count" as="xs:integer"/>
> 
> <xsl:function name="wl:div2">
>   <xsl:param name="num"  as="xs:double"/>
>   <xsl:param name="count" as="xs:integer"/>
>   <xsl:if test="$count > 0">
>     <xsl:value-of select="$num"/><xsl:text> </xsl:text>
>     <xsl:value-of select="wl:div2($num div 1024,$count - 1)"/>
>   </xsl:if>
> </xsl:function>
> 
> <xsl:template name="iter">
>   <xsl:value-of select="wl:div2($start,$count)"/> </xsl:template>
> 
> </xsl:stylesheet>