XSLT/Java: ERROR: 'Cannot find external method 'max' (must be public).'

Question

I am copying an example from XSLT Cookbook: 2nd Edition (O'Reilly: Mangano, 2006) where Mangano creates a tree diagram with SVG. As a way to quickly test this code, I am simply transforming the XML using JSTL's <x:transform/> tag, and running it in Jetty 6. The XSLT seems to be getting hung on calling java:java.lang.Math:max, saying:

ERROR: 'Cannot find external method 'max' (must be public).' FATAL ERROR: 'Could not compile stylesheet'

The code that gives me the error is contained in here where ...Math:max(... is called:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.1"
                xmlns:emath="http://www.exslt.org/math"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:tree="http://www.ora.com/XSLTCookboox/ns/tree"
                xmlns:xalan="http://xml.apache.org/xslt"
                xmlns:Math="xalan:java.lang.Math">
...
<!--Pass 1 copies input with added bookkeeping attributes -->  
<xsl:variable name="treeWithLayout">
  <xsl:apply-templates mode="layout"/>
</xsl:variable>

<xsl:variable name="maxPos" 
      select="Math:max($treeWithLayout/*/@tree:WEIGHT * 
                       ($nodeWidth + $horzSpace),
                       $treeWithLayout/*/@tree:MAXDEPTH * 
                         ($nodeHeight + $vertSpace))"/>
...

Answer 1

I found this usage online:

<xsl:stylesheet version="1.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:math="xalan://java.lang.Math"
  extension-element-prefixes="math">

Answer 2

You can get this message if there is any missing argument. For example:

You write

<xsl:variable name="maxPos" select="Math:max(9)"/>

instead

<xsl:variable name="maxPos" select="Math:max(9, 15)"/>