Why don't standard XPath functions work in XSLT?

Question

I'm having a lot of trouble trying to do some simple string processing in XSLT. What I would like to do is make selection using the standard xpath functions defined by the w3c. I'm using this as my cheat sheet:
http://w3schools.com/xpath/xpath_functions.asp
I've tried the default XSLT parser that comes with Java, the latest distro of Xalan and the latest distro of Saxon. Nothing seems to recognize the fn namespace:
xmlns:fn="http://www.w3.org/2005/02/xpath-functions"
In particular, I'm trying to use the tokenize(string, regex) function. Only Xalan seems to support this at all, only recognizes {http://xml.apache.org/xalan}tokenize, and it is treating the regex as a literal.
This is very frustrating. Is it possible to get the standard Xpath functions to work for XSLT?

Answer 1

How did you get it to work with Saxon? I have saxon9he.jar on my classpath. When I try to transform this:
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:src="http://xml.kitfox.com/schema/game/tileWorld/textTable"
    xmlns:xalan="http://xml.apache.org/xalan"
    xmlns:fn="http://www.w3.org/2005/02/xpath-functions"
    version="1.0">
    <xsl:output method="text"/>
<xsl:template match="/">
    <xsl:for-each select="fn:tokenize('a b c', '\s+')">
        "<xsl:value-of select="."/>"
    </xsl:for-each>
</xsl:template>
</xsl:stylesheet>I get the error
Error on line 100
  Cannot find a matching 2-argument function named
  {http://www.w3.org/2005/02/xpath-functions}tokenize()Is there some other jar you need to include to get http://www.w3.org/2005/02/xpath-functions to resolve?