Calculating day of the week XSL

Question

Trying to calculate day of the week number from date. Found some examples in the internet, but instead of day of the week number i see this : NaN.

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:strip-space elements="*"/>
  <xsl:output indent="yes"/>

  <xsl:template match="node()">
    <xsl:copy>
      <xsl:apply-templates/>
    </xsl:copy>
  </xsl:template>

  <xsl:template match="date">
    <xsl:copy>
      <xsl:call-template name="date-format">
        <xsl:with-param name="date-time" select="."/>
      </xsl:call-template>
    </xsl:copy>
  </xsl:template>

  <xsl:template name="date-format">
    <xsl:param name="date-time"/>
    <xsl:param name="date" select="substring-before($date-time,'T')"/>
    <xsl:param name="year" select="substring-before($date,'-')"/>
    <xsl:param name="month" 
          select="substring-before(substring-after($date,'-'),'-')"/>
    <xsl:param name="day" select="substring-after(substring-after($date,'-'),'-')"/>

    <xsl:variable name="a" select="floor((14 - $month) div 12)"/>
    <xsl:variable name="y" select="$year - $a"/>
    <xsl:variable name="m" select="$month + 12 * $a - 2"/>

    <xsl:value-of select="($day + $y + floor($y div 4) - floor($y div 100) 
    + floor($y div 400) + floor((31 * $m) div 12)) mod 7"/>

  </xsl:template>

</xsl:stylesheet>

.

<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet href="test2.xsl" type="text/xsl" ?>


<document>
  <date>2013-01-01</date>
  <date>2013-05-24</date>
  <date>2013-12-25</date>
  <date>1957-07-13</date>
  <date>1776-07-04</date>
</document>

Answer 1

The following stylesheet:

XSLT 1.0

<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:strip-space elements="*"/>

<xsl:template match="date">
    <xsl:call-template name="day-of-week">
        <xsl:with-param name="date" select="."/>
    </xsl:call-template>
</xsl:template>

<xsl:template name="day-of-week">
    <xsl:param name="date"/>

    <xsl:variable name="year" select="substring($date,1, 4)"/>
    <xsl:variable name="month" select="substring($date, 6, 2)"/>
    <xsl:variable name="day" select="substring($date, 9, 2)"/>

    <xsl:variable name="a" select="floor((14 - $month) div 12)"/>
    <xsl:variable name="y" select="$year + 4800 - $a"/>
    <xsl:variable name="m" select="$month + 12*$a - 3"/>

    <xsl:variable name="JDN" select="$day + floor((153*$m + 2) div 5) + 365*$y + floor($y div 4) - floor($y div 100) + floor($y div 400) - 32045" />

    <xsl:value-of select="($JDN + 1) mod 7" />
</xsl:template> 

</xsl:stylesheet>

when applied to your input example:

<document>
  <date>2013-01-01</date>
  <date>2013-05-24</date>
  <date>2013-12-25</date>
  <date>1957-07-13</date>
  <date>1776-07-04</date>
</document>

will return the following result:

<?xml version="1.0" encoding="UTF-8"?>
25364

---

Note:

The main problem with your attempt is this:

<xsl:param name="date" select="substring-before($date-time,'T')"/>

Your input has dates, not date-times, and they do not contain "T".