It is not necessary at all to use any extension functions.

Use the FXSL function f:arctan(), which is written completely in XSLT.

Here is an example:

When this transformation is applied on any xml document (ignored):

<xsl:stylesheet version="2.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:f="http://fxsl.sf.net/"
 >

  <xsl:import href="../f/func-arcTrignm.xsl" />

  <xsl:output method="text"/>

  <xsl:template match="/">
    <xsl:for-each select="1 to 10">
       <xsl:value-of select="f:arctan(1 div ., 0.000001, 'deg')"/>
       <xsl:text>&#xA;</xsl:text>
    </xsl:for-each>
  </xsl:template>
</xsl:stylesheet>

the result is:

45.000000000560625
26.565053176898004
18.434948193902347
14.036242861145283
11.309932383859845
9.462322136978774
8.130102294470776
7.125016296527626
6.340191698516003
5.710593093647205

I can see when calculating 1000 different values of f:arctan(), that
it takes arround 5 milliseconds per single calculation (and this
includes the time to output the 1000-line result)


-- 
Cheers,
Dimitre Novatchev
---------------------------------------
Truly great madness cannot be achieved without significant intelligence.
---------------------------------------
To invent, you need a good imagination and a pile of junk
-------------------------------------
Never fight an inanimate object
-------------------------------------
You've achieved success in your field when you don't know whether what
you're doing is work or play




On Wed, Mar 19, 2008 at 7:18 AM, Patrick Bergeron <pbergeron@xxxxxxxxxxx> wrote:
> Hello,
>
> I'm trying to make a small template that concisely implements atan2, but
> returns the values in degrees and handles the case where DX is zero.  So
> far, I have:
>
>
>        <xsl:template name="my_atan2">
>                <xsl:param name="dx" />
>                <xsl:param name="dy" />
>
>                <xsl:variable name="rad" >
>                        <xsl:choose>
>                                <xsl:when test="dx != 0">
>                                        <xsl:value-of select="exsl:atan2(dx,
> dy)" />
>                                </xsl:when>
>
>                                <xsl:when test="(dx = 0) and (dy &gt; 0)">
>                                    <xsl:value-of select="$my_pi" />
>                                </xsl:when>
>
>                                <xsl:when test="(dx = 0) and (dy &lt; 0)">
>                                    <xsl:value-of select="$my_pi * 3" />
>                                </xsl:when>
>                        </xsl:choose>
>                </xsl:variable>
>
>                <xsl:choose>
>                        <xsl:when test="$rad &lt; 0">
>                                <xsl:value-of select="($rad * 180 div
> $my_pi) + 360" />
>                        </xsl:when>
>
>                        <xsl:otherwise>
>                                <xsl:value-of select="($rad * 180 div
> $my_pi)" />
>                        </xsl:otherwise>
>                </xsl:choose>
>        </xsl:template>
>
>
> Is there a way to express this in only a few lines without all the
> verbosity?