XSLT Reference

abs()

XSLT 2.0 numeric function

Returns the absolute value of a numeric argument, removing any negative sign while preserving the numeric type.

Syntax

abs(number)

Description

abs() returns the absolute (non-negative) value of its argument. The result has the same type as the input: xs:integer in gives xs:integer out, xs:double in gives xs:double out. If the argument is the empty sequence, the empty sequence is returned.

Parameters

Parameter	Type	Required	Description
`number`	xs:numeric?	Yes	The numeric value whose absolute value is required.

Return value

xs:numeric? — same type and precision as the input, but non-negative. Returns the empty sequence if the argument is the empty sequence.

Examples

Absolute value of a negative attribute

Input XML:

<?xml version="1.0" encoding="UTF-8"?>
<measurements>
  <value>-42</value>
  <value>17</value>
  <value>-3.14</value>
</measurements>

Stylesheet:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xsl:output method="xml" indent="yes"/>

  <xsl:template match="/measurements">
    <absolutes>
      <xsl:for-each select="value">
        <abs><xsl:value-of select="abs(xs:decimal(.))"/></abs>
      </xsl:for-each>
    </absolutes>
  </xsl:template>
</xsl:stylesheet>

Output:

<absolutes>
  <abs>42</abs>
  <abs>17</abs>
  <abs>3.14</abs>
</absolutes>

Computing deviation from a target value

Stylesheet:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xsl:output method="xml" indent="yes"/>

  <xsl:template match="/measurements">
    <deviations>
      <xsl:variable name="target" select="xs:decimal(10)"/>
      <xsl:for-each select="value">
        <deviation><xsl:value-of select="abs(xs:decimal(.) - $target)"/></deviation>
      </xsl:for-each>
    </deviations>
  </xsl:template>
</xsl:stylesheet>

Output (for values -42, 17, -3.14 against target 10):

<deviations>
  <deviation>52</deviation>
  <deviation>7</deviation>
  <deviation>13.14</deviation>
</deviations>

Notes

abs() is defined in XPath 2.0 and is not available in XSLT 1.0. In XSLT 1.0, absolute value required a workaround such as translate(., '-', '') or a conditional expression.
The function preserves numeric type: abs(xs:float(-1.0)) returns xs:float(1.0).
abs(xs:double('NaN')) returns NaN; abs(xs:double('-INF')) returns INF.