Re: IEEE arithmetic handling

eggert@twinsun.com (Paul Eggert)
Tue, 17 Nov 1992 18:58:37 GMT

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Newsgroups: comp.compilers
From: eggert@twinsun.com (Paul Eggert)
Organization: Twin Sun, Inc
Date: Tue, 17 Nov 1992 18:58:37 GMT
References: 92-11-041 92-11-087
Keywords: arithmetic

bill@amber.csd.harris.com (Bill Leonard) writes:


>Fortran does not *conflict* with the IEEE vis-a-vis negative zero. It merely
>says that the processor must never *output* a negatively-signed zero.


But that conflicts with IEEE Std 754-1985, section 5.6, which requires
that converting a number from binary to decimal and back be the identity
if the proper precision and rounding is used. The Fortran standard says
-0.0 must be output as 0.0; this loses information.


One way to work around the problem is to supply IEEE-specific
binary/decimal conversion routines to the Fortran programmer, but there's
no standard for this, and most implementors don't bother. So in practice,
I'm afraid that Fortran and IEEE are indeed in conflict here.
--


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