<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Oct 20, 2020, at 5:02 PM, Damian McGuckin <<a href="mailto:damianm@esi.com.au" class="">damianm@esi.com.au</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class=""><br class="">Hi Jim,<br class=""><br class="">On Tue, 20 Oct 2020, Jim Thomas wrote:<br class=""><br class=""><blockquote type="cite" class="">The definitions are in 7.12.1 in<br class=""><a href="http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2573.pdf" class="">http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2573.pdf</a><br class="">I assume you?re asking about the C standard.<br class=""></blockquote><br class="">Because if you look there, the word underflow is used long before it appears in any definition.<br class=""><br class="">On page 450,<br class=""><br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>The "underflow" floating-point exception is raised whenever a<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>result is tiny (essentially subnormal or zero) and suffers loss of<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>accuracy.<br class=""></div></div></blockquote><div><br class=""></div><div>This is in Annex F and is suppose to reflect the IEC 60559 definition. An update here is needed.</div><div><br class=""></div><div>The discussion Fred is raising is about the C definition of underflow, in 7.12.1. Ideally, the C definition would not be inconsistent with the (correct) IEC 60559 one.</div><br class=""><blockquote type="cite" class=""><div class=""><div class=""><br class="">Given:<br class=""><br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>0.25 * 2**emin<br class=""><br class="">does this overflow. Because it is exact. But is Page 450 the strict definition. Because, that answers Fred's question (and agrees with Fred).<br class=""><br class="">I actually meant in the latest IEEE 754 (or IEC).<br class=""></div></div></blockquote><div><br class=""></div>See 7.5 in</div><div><br class=""></div><div><a href="https://wiki.edg.com/pub/CFP/WebHome/754-2019.pdf" class="">https://wiki.edg.com/pub/CFP/WebHome/754-2019.pdf</a></div><div><br class=""></div><div>- Jim Thomas</div><div><br class=""><blockquote type="cite" class=""><div class=""><div class=""><br class="">Sorry, if I seem rushed. I am off to two meetings and did not have time to look it up as thoroughly as I would have liked. But I wanted to get the email out before your part of the world went to bed.<br class=""><br class="">Regards - Damian<br class=""><br class="">Pacific Engineering Systems International, 277-279 Broadway, Glebe NSW 2037<br class="">Ph:+61-2-8571-0847 .. Fx:+61-2-9692-9623 | unsolicited email not wanted here<br class="">Views & opinions here are mine and not those of any past or present employer<br class=""></div></div></blockquote></div><br class=""></div></body></html>