09-223r1 To: J3 Members From: Stan Whitlock Subject: J3 Fortran interp F03/0022 Date: 2009 May 6 NUMBER: F03/0022 TITLE: Coexistence of IEEE and non-IEEE kinds KEYWORDS: IEEE, kind DEFECT TYPE: Interpretation STATUS: Passed by J3 meeting QUESTION: Is it allowed for a processor to have one or more real kinds for which there is no IEEE support, while also having real kinds for which there is IEEE support? Much of the IEEE material appears to assume that a processor could simultaneously support both IEEE and non-IEEE kinds. I thought this was the intent. However, the first sentence of the second paragraph in section 14 says that if IEEE_EXCEPTIONS or IEEE_ARITHMETIC is accessible in a scoping unit, then IEEE_OVERFLOW and IEEE_DIVIDE_BY_ZERO are supported in the scoping unit for *ALL* [emphasis mine] kinds of real and complex data. This says to me that if there is any kind of real for which the processor cannot support IEEE_OVERFLOW or IEEE_DIVIDE_BY_ZERO, then pretty much none of the IEEE stuff can be used on that processor at all; there isn't much of the IEEE stuff that can be used without IEEE_ARITHMETIC or IEEE_EXCEPTIONS. This seems draconian and unintended. I speculate that this condition is intended to apply to all IEEE real kinds rather than to all real kinds. ANSWER: Yes, this is allowed. The requirement that IEEE_OVERFLOW and IEEE_DIVIDE_BY_ZERO be supported for all kinds of real and complex data within that scoping unit was unintentional. Support of these two flags means that the exceptions can be detected for real and complex kinds that are IEEE floating point data. The Standard makes no claims about non-IEEE kinds. An edit is provided to clarify this. EDITS: All edits pertain to 04-007. Clause 14 "Exceptions and IEEE arithmetic", 1st sentence of 2nd paragraph [363:9-10] replace "for all kinds of real and complex data" with "for all kinds of real and complex IEEE floating-point data" SUBMITTED BY: Richard Maine HISTORY: 04-419 m170 F03/0022 submitted 04-419r1 m170 Passed by J3 meeting 05-146 m171 Failed J3 letter ballot #10 09-223 m188 Revised answer 09-223r1 m188 Passed by J3 meeting