X-Authentication-Warning: delorie.com: mail set sender to djgpp-workers-bounces using -f Date: Thu, 19 Feb 2004 11:58:38 -0600 From: Eric Rudd Subject: Re: C99 Functions Under Development and Checkout In-reply-to: <1d2.19fe4c86.2d64ee60@aol.com> To: djgpp-workers AT delorie DOT com Message-id: <4034F94E.4070308@cyberoptics.com> Organization: CyberOptics MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit X-Accept-Language: en,pdf User-Agent: Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.5) Gecko/20030925 References: <1d2 DOT 19fe4c86 DOT 2d64ee60 AT aol DOT com> X-MailScanner-Information: Please contact the ISP for more information X-MailScanner: Found to be clean Reply-To: djgpp-workers AT delorie DOT com Errors-To: nobody AT delorie DOT com X-Mailing-List: djgpp-workers AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk Kbwms AT aol DOT com wrote: >In a message dated 2/18/2004 10:42:56 AM Eastern Standard Time, >rudd AT cyberoptics DOT com writes: > >>ince, for example, inf/inf is outside the domain over which the arc >>tangent function is defined, it would seem that a domain error should occur. >> >It is not clear to which function you are referring. The case atan2(Y, X) is >handled in the standard: > > If Y is +-Inf and X is -Inf, +-3pi/4 shall be returned. > If Y is +-Inf and X is +Inf, +-pi/4 shall be returned. > I am referring to the arc tangent function, as it is understood by mathematicians. The behavior of atan2() is defined in Annex F for implementations conforming to IEC60559 (which is where you quoted from, I'm guessing), but I interpret the 7.12.1 clause as specifying a domain error when the corresponding mathematical function is undefined -- hence the reference to mathematics. The mathematical arc tangent function is not defined for an undefined argument, so there would seem to be a contradiction between that and Annex F. -Eric Rudd