More efficient max() algorithm (Was: Re: Re: [xsl] Max value from a table )

[Dimitre Novatchev <dnovatchev at yahoo dot com>]

> <?xml version="1.0"?>
> <xsl:stylesheet version="1.0"
> xmlns:xsl="http://www.w3.org/1999/XSL/Transform";;>
>   <xsl:output indent="yes"/>
> 
> <xsl:variable name="max">
>     <xsl:for-each select="/table/row/col">
>         <xsl:sort select="text()" data-type="number" order="descending"/>
>         <xsl:if test="position() = 1">
>            <xsl:value-of select="text()"/>
>        </xsl:if>
>    </xsl:for-each>
> </xsl:variable>

This algorithm, as the one currently presented in the XSLT-FAQ, is O(N * Log2(N))
complex.
There exists an O(N) algorithm -- look for it in the Jan/Feb threads of this group
or in the generic templates download at vbxml.com.
This algorithm uses simple recursion and may crash some XSLT processors.

Another O(n) algorithm, which might be the fastest on a parallel processor
environment and which has minimum recursion depth -- this is a Divide and Conquer
algorithm for max().

Cheers,
Dimitre Novatchev.




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