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

["Roger L Costello costello@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Michael Kay wrote:

(4.99 * 10 idiv 10) gives 4.9

But, but, but, .

4.99 * 10 = 49.9
49.9 idiv 10 = 4

Right?

/Roger

From: Michael Kay mike@xxxxxxxxxxxx <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
Sent: Tuesday, June 23, 2020 11:48 AM
To: xsl-list <xsl-list@xxxxxxxxxxxxxxxxxxxxxx>
Subject: [EXT] Re: [xsl] Function that reduces the number of digits to the
rightof the decimal point?

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 mailto:costello@xxxxxxxxx
<mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> 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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