RE: [xsl] Calculations involving measurements with units

["Ragulf Pickaxe" <jawxml@xxxxxxxxxxx>]

Hello Paul,

<xsl:variable name="upper-margin" select="number($page-height) / 3.75"/>

The number function returns NaN when the string cannot be expressed as a 
number - therefore this goes wrong.

If you know the units beforehand (i.e. always mm), then you can do:
<xsl:variable name="upper-margin" 
select="concat(number(translate($page-height, 'm', '')) / 3.75, 'mm')"/>
which throws away the m's. Then appends mm to the answer.

If you do not know beforehand the units, but need them from the string, then 
you can do a recursive solution taking one letter at a time, checking if it 
is a number. If it is not a number, you print out the units.

For example:
<xsl:variable name="Unit">
 <xsl:call-template name="TakeOutUnit">
   <xsl:with-param name="IsNumber" select="$page-height"/>
 </xsl:call-template>
</xsl:variable>

<xsl:variable name="upper-margin" 
select="concat(number(translate($page-height, 'abcdefghijklmnopqrstuvwxyz', 
'')) / 3.75, $Unit)"/>
<!-- Assuming that the units can only be in small letters -->

<xsl:template name="TakeOutUnit">
 <xsl:param name="IsNumber"/>
   <xsl:xhoose>
     <xsl:when test="number(substring($IsNumber, 1, 1))!=NaN">
       <xsl:call-template name="TakeOutUnit">
         <xsl:with-param name="IsNumber" select="substring($IsNumber, 2, (1 
div 0))"/>
       </xsl:call-template>
     </xsl:when>
     <xsl:otherwise>
       <xsl:value-of select="$IsNumber"/>
       <!-- We assume that when the first character is not a number, then 
we have the unit -->
     </xsl:otherwise>
   </xsl:choose>
</xsl:template>


Hope this helps,

Regards,
Ragulf :)

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