<xsl:with-param name="end"><xsl:value-of 
select="$end"/></xsl:with-param>

it won't affect the result but it's a lot more efficient to do

  <xsl:with-param name="end" select="$end"/>

(always, not just in this example) as with the first form  the number
has to be serialised to a decimal string representation, and a result
tree fragment constructed witha root node and child a text node with
string value that representation. When used, it is coerced back to being
a number.

With the second form $end is just passed the value that it had, which
will be a number (that is, an ieee double).

David

________________________________________________________________________
The Numerical Algorithms Group Ltd is a company registered in England
and Wales with company number 1249803. The registered office is:
Wilkinson House, Jordan Hill Road, Oxford OX2 8DR, United Kingdom.

This e-mail has been scanned for all viruses by Star. The service is
powered by MessageLabs. 
________________________________________________________________________