Thu, 25 Oct 90 01:06:04 GMT

Related articles |
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IEEE 754 vs Fortran arithmetic robertsj@admin.ogi.edu (John Roberts) (1990-10-22) |

Re: IEEE 754 vs Fortran arithmetic burley@world.std.com (1990-10-24) |

Re: IEEE 754 vs Fortran arithmetic henry@zoo.toronto.edu (1990-10-24) |

Re: IEEE 754 vs Fortran arithmetic tim@ksr.com (Tim Peters) (1990-10-24) |

Re: IEEE 754 vs Fortran arithmetic dik@cwi.nl (1990-10-25) |

Re: IEEE 754 vs Fortran arithmetic wsb@eng.Sun.COM (1990-10-25) |

Re: IEEE 754 vs Fortran arithmetic eggert@twinsun.com (1990-10-25) |

Re: IEEE 754 vs Fortran arithmetic wsb@eng.Sun.COM (1990-10-25) |

Re: IEEE 754 vs Fortran arithmetic sjc@key.COM (1990-10-26) |

Re: IEEE 754 vs Fortran arithmetic diamond@tkov50.enet.dec.com (1990-10-15) |

Re: IEEE 754 vs Fortran arithmetic tim@ksr.com (Tim Peters) (1990-10-27) |

Re: IEEE 754 vs Fortran arithmetic bsy+@CS.CMU.EDU (Bennet Yee) (1990-10-28) |

Re: IEEE 754 vs Fortran arithmetic mcohen@amsaa-seer.brl.mil (Marty Cohen) (1990-10-30) |

Newsgroups: | comp.compilers,comp.lang.fortran |

From: | eggert@twinsun.com (Paul Eggert) |

Keywords: | Fortran |

Organization: | Twin Sun, Inc |

References: | <9010230628.AA22160@admin.ogi.edu> <1990Oct24.162529.20452@zoo.toronto.edu> |

Date: | Thu, 25 Oct 90 01:06:04 GMT |

*>[Given that +0 = -0, it's not clear to me that the existence of -0 breaks*

*>anything. Keep in mind that F77 is a permissive standard.... -John]*

Not permissive enough, unfortunately: IEEE's -0.0 breaks F77's input/output.

ANSI X3.9-1978 says that -0.0 and +0.0 must print the same way. IEEE 754-1985

says that -0.0 and +0.0 are distinct, and that printing any number and reading

it back in must yield the original number if the proper precision is used.

These provisions contradict each other. An implementation cannot conform to

both standards without unnatural contortions. I suspect most F77

implementations simply ignore the IEEE requirement here.

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