XSLT: Handling numeric values that use exponent notation - xslt

Question

We have to transform some XML that contain numbers in exponent (aka scientific) notation
eg.
<Value>12.34e12</Value>
<Value>-12.34e-12</Value>
rather irritatingly, we cannot use the sum() function and the like because the XSLT parser expects numbers to be in decimal format.
[We are using the .Net XslCompiledTransform class to do the transform but I think this problem is common to all XSLT implementations]
The only solution to this problem that we have so far is to transform the string value to a number using a javascript function (see below) and then write our own sum template which calls this function.
It seems to me that there must be a better way - is there?
/*
This function attempts to coerce the input into a number.
*/
function toNumber( x ) {
if(!x) {
return Number.NaN;
}
if(typeof x === 'number') {
return x;
}
return parseFloat(x);
};

Answer 1

Saxon-B 9.0.0.6 works fine here. Outputs 0.
EDIT: Now I see that Saxon 6 (processor only for xslt 1.0) returns NaN. But if you try xslt 2.0, you won't ever want anything else. :-)
XML:
<?xml version="1.0" encoding="UTF-8"?>
<root>
<Value>12.34e12</Value>
<Value>-12.34e12</Value>
</root>
XSLT:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:template match="root">
<xsl:value-of select="sum(Value)"/>
</xsl:template>
</xsl:stylesheet>