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## Re: floor, ceil, trunc, round, minus zero, and alpha

**From**: |
Bruno Haible |

**Subject**: |
Re: floor, ceil, trunc, round, minus zero, and alpha |

**Date**: |
Mon, 20 Dec 2010 16:44:45 +0100 |

**User-agent**: |
KMail/1.9.9 |

Eric Blake wrote:
>* > - are marked as [MX] in POSIX [1][2][3][4], that is, an optional feature*
>* > not contained in ISO C 99,*
>* *
>* [MX] means that the behavior is required on platforms that claim IEC*
>* 60559 conformance (aka IEEE 754 format); it means that you fully*
>* implement the otherwise-optional Appendix F of the C99 standard.*
I see. Thanks for correcting me.
Regarding DEC Alpha platforms, I don't think they are 100% IEEE 754 + 854
compliant, because the hardware designers took some shortcuts regarding
the exception handling, in order to implement the floating-point operations
in a single CPU cycle.
>* > - make little sense for 'ceil' from a mathematical point of view:*
>* > ceil is a monotonically increasing function but POSIX wants*
>* > ceil(-0.5) = 0.0 and ceil(-0.0) = -0.0,*
>* *
>* I'll raise that point with the Austin group.*
Given that the annex section F.9.6.1 in ISO C99 already specifies this
behaviour, I don't think the Austin group will deviate from that.
Bruno

**floor, ceil, trunc, round, minus zero, and alpha**, *Bruno Haible*, `2010/12/20`
**Re: floor, ceil, trunc, round, minus zero, and alpha**, *Eric Blake*, `2010/12/20`
**Re: floor, ceil, trunc, round, minus zero, and alpha**,
*Bruno Haible* **<=**
**Re: floor, ceil, trunc, round, minus zero, and alpha**, *Eric Blake*, `2010/12/20`
**Re: floor, ceil, trunc, round, minus zero, and alpha**, *Bruno Haible*, `2010/12/20`
**Re: floor, ceil, trunc, round, minus zero, and alpha**, *Paul Eggert*, `2010/12/20`
**Re: floor, ceil, trunc, round, minus zero, and alpha**, *Bruno Haible*, `2010/12/20`
**Re: floor, ceil, trunc, round, minus zero, and alpha**, *Bruno Haible*, `2010/12/22`
**Re: floor, ceil, trunc, round, minus zero, and alpha**, *Eric Blake*, `2010/12/20`
**Re: floor, ceil, trunc, round, minus zero, and alpha**, *Bruno Haible*, `2010/12/22`

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