Article View: comp.std.c
Article #1342Re: Questions about NCEG
From: Andrew P. Mullhaupt
Date: Thu, 31 May 1990 03:10
Date: Thu, 31 May 1990 03:10
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1542 bytes
In article <1990May29.193451.6533@twinsun.com>, eggert@twinsun.com (Paul Eggert) writes: > There are ways to say the IEEE numbers in ANSI C + IEEE 754: > #define infinity (1e300*1e300) > This lets you say some things portably that you can't say with hex contants, Will this work if the compiler supports IEEE extended format for constants? Or would this preclude ANSI C compliance? The constant 1e600 is not out of extended range. You might replace 1e300 in your example by a larger number, but then what about the compilers which _don't_ use extended? Both behaviors are permitted by IEEE arithmetic. A conditional compilation solution is possible only if you can ensure that the appropriate symbol will be defined. Once you've been reduced to that, you should use the hex constant method, on the grounds that even on the same hardware, different compilers, or even different preprocessors for the same compiler may handle the constant arithmetic differently, but the floating point representation is less likely to change. Later, Andrew Mullhaupt
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!samsung!uunet!mstan!amull From: amull@Morgan.COM (Andrew P. Mullhaupt) Newsgroups: comp.std.c Subject: Re: Questions about NCEG Summary: Really? Message-ID: <1008@s6.Morgan.COM> Date: 31 May 90 03:10:15 GMT References: <15519@bfmny0.UU.NET> <73.UUL1.3#5109@pantor.UUCP> <1990May29.193451.6533@twinsun.com> Organization: Morgan Stanley & Co. NY, NY Lines: 21