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Re: [xsl] Function that reduces the number of digits to the right of the decimal point?

2020-06-23 10:48:30
Do you absolutely want truncation (so 4.99 becomes 4.9) or will rounding do (so 
4.99 becomes 5.0)?

If rounding will do, then use round($x, -$desired-digits).

If you really want truncation then consider the "idiv" operator, for example 
(4.99 * 10 idiv 10) gives 4.9: you can construct the value 10 as math:pow(10, 
$desired-digits).

Michael Kay
Saxonica

On 23 Jun 2020, at 15:28, Roger L Costello costello(_at_)mitre(_dot_)org 
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

Hi Folks,

$num is a variable holding a decimal value.

$desired-number-of-digits-after-decimal-point is a variable holding an 
integer value. 

I want a function that reduces the number of digits to the right of the 
decimal point in $num according to the value specified in 
$desired-number-of-digits-after-decimal-point

Example #1:
$num = 42.366978
$desired-number-of-digits-after-decimal-point = 2
The result of applying the function is: 42.36

Example #2:
$num = 42.366978
$desired-number-of-digits-after-decimal-point = 0
The result of applying the function is: 42

Below is one way to implement the function. Is there a better way? By 
"better" I mean simpler, more correct. 

Also, is there a better name for the function?  By "better" I mean shorter, 
more standardized. /Roger
-----------------------------------------------------
<xsl:function name="f:reduce-number-of-digits-after-decimal-point" 
as="xs:string">
   <xsl:param name="num" as="xs:string" />
   <xsl:param name="desired-number-of-digits-after-decimal-point" 
as="xs:integer" />

   <xsl:variable name="whole-part" select="substring-before($num, '.')"/>
   <xsl:variable name="fraction-part" select="substring-after($num, '.')"/>
   <xsl:variable name="reduced-fraction-part" 
select="substring($fraction-part, 1, 
$desired-number-of-digits-after-decimal-point)"/>
   <xsl:choose>
       <xsl:when test="$desired-number-of-digits-after-decimal-point gt 0">
           <xsl:value-of select="concat($whole-part, '.', 
$reduced-fraction-part)"/>
       </xsl:when>
       <xsl:otherwise>
           <xsl:value-of select="$whole-part"/>
       </xsl:otherwise>
   </xsl:choose>
</xsl:function>

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