From owner-sc22wg5+sc22wg5-dom8=www.open-std.org@open-std.org Fri Jul 4 02:37:25 2014 Return-Path: X-Original-To: sc22wg5-dom8 Delivered-To: sc22wg5-dom8@www.open-std.org Received: by www.open-std.org (Postfix, from userid 521) id 7E13B358314; Fri, 4 Jul 2014 02:37:25 +0200 (CEST) Delivered-To: sc22wg5@open-std.org Received: from nag-j.co.jp (nag-j.co.jp [111.68.142.10]) by www.open-std.org (Postfix) with ESMTP id ADE723566AA for ; Fri, 4 Jul 2014 02:37:20 +0200 (CEST) Received: from Maru6 (218-42-159-105.cust.bit-drive.ne.jp [218.42.159.105]) (authenticated bits=0) by nag-j.co.jp (8.14.5/8.14.5) with ESMTP id s640bEul041471 for ; Fri, 4 Jul 2014 09:37:21 +0900 (JST) (envelope-from malcolm@nag-j.co.jp) Message-ID: From: "Malcolm Cohen" To: "WG5" References: <20140702232501.1F2EE35877B@www.open-std.org><20140703175703.0B23F3587E3@www.open-std.org> <20140703194324.CB8E9358758@www.open-std.org> In-Reply-To: <20140703194324.CB8E9358758@www.open-std.org> Subject: Re: [ukfortran] (SC22WG5.5300) Did we intend to prohibit this? Date: Fri, 4 Jul 2014 09:37:12 +0900 Organization: =?utf-8?B?5pel5pysTkFH?= MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="utf-8"; reply-type=response Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 15.4.3555.308 X-MimeOLE: Produced By Microsoft MimeOLE V15.4.3555.308 Sender: owner-sc22wg5@open-std.org Precedence: bulk > integer, parameter :: RK = kind(1.0e0) > real(rk), parameter :: SNaN = merge( IEEE_Value(1.0_rk,IEEE_Signaling_NaN), & > & 0.0_rk, IEEE_Support_DataType(1.0_rk) ) This would in any case not be conforming when either IEEE_SUPPORT_DATATYPE is false or IEEE_SUPPORT_NAN is false, since MERGE is not "short-cut" evaluation. There are many traps and pitfalls associated with trying to use signalling NaN in user code, especially in code that might be evaluated at compile-time. I would not recommend embarking on such a journey. Cheers, -- ................................Malcolm Cohen, Nihon NAG, Tokyo.