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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#212121">CFP met today and discussed this. We agree with your first point and are good with the proposed new text (the part after “It should read”).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#212121"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#212121">Please feel free to bring this forword as a proposal to WG14, or if you prefer, let CFP know and we can do it.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">cfp-interest <cfp-interest-bounces@oakapple.net> on behalf of Javier Múgica <javier@aerotri.es><br>
<b>Date: </b>Sunday, April 13, 2025 at 10:11</span><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"> </span><span style="font-size:12.0pt;color:black">PM<br>
<b>To: </b>cfp-interest <cfp-interest@ucbtest.org>, jaswthomas <jaswthomas@sbcglobal.net><br>
<b>Subject: </b>[EXTERNAL] [cfp-interest 3431] Range error conditions for atan2 and atan2pi<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">I have come across the condition for domain error and range error for several functions, and I bring to points to your attention:<br>
<br>
--------- 1st<br>
<br>
atan2:<br>
<br>
The atan2 functions [...]. A domain error may occur if both arguments are zero. A range error occurs if x is positive and nonzero y/x is too close to zero.<br>
<br>
The last sentence reads, in English, "A range error occurs if (x is (positive and nonzero) y/x is too close to zero)."<br>
<br>
and there seems to be a missing "and". But reading the analogous sentence for other functions, e.g., atan:<br>
<br>
The atan functions compute the principal value of the arc tangent of x. A range error occurs if nonzero x is too close to zero.<br>
<br>
one can guess the intended meaning. It should read:<br>
<br>
A range error occurs if x is positive and if y/x is nonzero and too close to zero.<br>
<br>
--------- 2nd<br>
<br>
Why "positive"? Considering that atan2 is an odd function, +x and -x should give +alpha and -alpha uniformly. The "atan", "sin", "tan", etc. functions don't make this distinction. Its presence in atan2 and atan2pi seems spurious.<br>
This distinction is present in exponential functions, but there it makes sense.<br>
<br>
<br>
Regards,<br>
<br>
Javier Múgica<br>
<br>
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