Extensions to XSLT 1.0 (EXSLT 1.0) - Math

This version: exslt-math-010310.html
Most Recent version: http://www.jenitennison.com/xslt/exslt/math/
Previous version: exslt-math-010302.html
Author: Jeni Tennison

Abstract

This document describes EXSLT 1.0 - Math. EXSLT 1.0 is a set of extension elements and functions that XSLT authors may find helpful when creating stylesheets. EXSLT 1.0 - Math covers those extension elements and functions that provide facilities to do with maths.

Other parts of EXSLT 1.0 include:

Status of this Document

This document is a second draft for review by the implementers of XSLT processors and the XSLT stylesheet authors. It is based on discussions on XSL-List. Comments on this document should be sent to XSL-List.

This document has no official standing and has not been considered nor approved by any organization.

Contents

1. Introduction
2. Namespace
3. Math Functions

Appendices

A. References
B. Implementations in EXSLT
C. Acknowledgements
D. Changes from Previous Version

1. Introduction

This document describes EXSLT 1.0 - Math. EXSLT 1.0 is a set of extension elements and functions that XSLT authors may find helpful when creating stylesheets. EXSLT 1.0 - Math covers those extension elements and functions that provide facilities to do with maths.

The extension elements and functions defined within this document are governed by the general rules about extensions to XSLT covered in [14. Extensions] in [XSLT 1.0].

XSLT processors are free to support any number of the extension elements and functions described in this document. However, an XSLT processor must not claim to support EXSLT 1.0 - Math unless all the extensions described within this document are implemented by the processor. An implementation of an extension element or function in an EXSLT namespace must conform to the behaviour described in this document.

2. Namespace

The namespace for the extension elements and functions described in this document is: 

http://xmlns.opentechnology.org/xslt-extensions/math

Throughout this document, the prefix math is used to refer to this namespace. Any other prefix can be used within a particular stylesheet (though a prefix must be specified to enable the extension functions to be recognised as extensions).

3. Math Functions

This section defines the extension functions in EXSLT 1.0 - Math.

Function: number math:max(node-set)

The math:max function returns the maximum, for each node in the argument node-set, of the result of converting the string-values of the node to a number using the number function. The numbers are compared as with the > operator. If the node set is empty, NaN is returned.

Function: number math:min(node-set)

The math:min function returns the maximum, for each node in the argument node-set, of the result of converting the string-values of the node to a number using the number function. The numbers are compared as with the < operator. If the node set is empty, NaN is returned.

Function: node-set math:highest(node-set)

The math:highest function returns the nodes for which the result of converting the string-value of the node to a number is maximum value for the node set, as calculated with math:max.

Function: node-set math:lowest(node-set)

The math:lowest function returns the nodes for which the result of converting the string-value of the node to a number is minimum value for the node set, as calculated with math:min.

A. References

EXSLT Common
Jeni Tennison. Extensions to XSLT 1.0 (EXSLT 1.0) - Common. See http://www.jenitennison.com/xslt/exslt/common
XSLT
World Wide Web Consortium. XSL Transformations (XSLT). W3C Recommendation. See http://www.w3.org/TR/xslt
XPath
World Wide Web Consortium. XML Path Language. W3C Recommendation. See http://www.w3.org/TR/xpath

B. Sample Extension Functions

This appendix holds example implementations of the functions defined in this document, using exsl:function as described in [EXSLT Common].

Function: number math:max(node-set, string?) 

<exsl:function name="math:max">
   <xsl:param name="node-set" select="/.." />
   <exsl:result select="number($node-set[not($node-set > .)])" />
</exsl:function>

Function: number math:min(node-set, string?) 

<exsl:function name="math:min">
   <xsl:param name="node-set" select="/.." />
   <exsl:result select="number($node-set[not($node-set &lt; .)])" />
</exsl:function>

Function: node-set math:highest(node-set, string?) 

<exsl:function name="math:highest">
   <xsl:param name="node-set" select="/.." />
   <exsl:result select="$node-set[not($node-set > .)]" />
</exsl:function>

Function: node-set math:lowest(node-set, string?) 

<exsl:function name="math:lowest">
   <xsl:param name="node-set" select="/.." />
   <exsl:result select="$node-set[not($node-set &lt; .)]" />
</exsl:function>

C. Acknowledgements

This document describes functions that are currently in use in Saxon by Mike Kay. It has also been informed and inspired by discussions on XSL-List.

Also many thanks to Uche Ogbuji for his comments following implementation of these functions in 4XSLT.

D. Changes from Previous Version