maths in XML ???

Somewhere on the web i read an example but I am unable to understand it. Can anyone help?

xml file

xsl file

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
     version="1.0">
<xsl [img]http://www.javaranch.com/ubb/redface.gif[/img]utput method="xml" omit-xml-declaration="yes"/>
<xsl:template match="numbers">
  A. 4 + 3.2        = <xsl:value-of select="x + y"/>
  B. 3.2 - 4        = <xsl:value-of select="y - x"/>
  C. 4 * 3.2        = <xsl:value-of select="x * y"/>
  D. 11/3.2         = <xsl:value-of select="z div y"/>
  E. 4 + 3.2 * 11   = <xsl:value-of select="x+y*z"/>
  F. (4 + 3.2) * 11 = <xsl:value-of select="(x+y)*z"/>
  G. 11 mod 4       = <xsl:value-of select="z mod x"/>
  H. 4 + 3.2 + 11   = <xsl:value-of select="sum(*)"/>
  I. floor(3.2)     = <xsl:value-of select="floor(y)"/>
  J. ceiling(3.2)   = <xsl:value-of select="ceiling(y)"/>
  K. round(3.2)     = <xsl:value-of select="round(y)"/>
  L. 11 + count(*)  = <xsl:value-of select="11+count(*)"/>
  M. 3.2 + string-length("3.2") = 
     <xsl:value-of select="y + string-length(y)"/>
  N. 11 + "hello"     = <xsl:value-of select="z + 'hello'"/>
</xsl:template>
</xsl:stylesheet>

I hope the following helps:
<xsl:template match="numbers"> indicates that we want to work with the <numbers> node(s).
After that is a list from A through N. The left of "=" describes what we want to do in terms that we can understand outside of xsl. The right of "=" shows how this is done in xsl.
For example:
<xsl:value-of select="x+y"/> says to take the value of the nodes <x> and <y> (remember we are dealing with children of <numbers> ), and add them together to get the desired result. In this case we would get an out put of 7.2.
I hope this helps.

Thanks for the explanation. But I can't get any output.

I am not sure how to help you get output. I am fairly new to XML also, but I can tell you what I did.
I followed an example in "Beginning XML" from Wrox Press which instructed me to use XT, which is available from http://www.jclark.com/xml/xt.html, as the transformation engine. I then ran xt.exe from the command line:
xt <name of xml file> <name of xsl file> <optional: name of output file>
If you leave out the output file the result of the transformation will appear in the command prompt window. This worked for me and gave me the results I expected.
I would suggest finding a simple example of using XSLT in a book or on a website and try to duplicate it's results, then apply that to your xml and xsl files to see what happens.
Good luck!

"Match" example was described in Bob DuCharme's "Math and XSLT" article: http://www.xml.com/pub/a/2001/05/07/xsltmath.html
you cannot run it only with XML, you need some XSLT processor, for example XT, like Tony said.

Thanks. The example cleared the doubts.