Sat, 29 Apr 1995 04:47:08 GMT

Related articles |
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[12 earlier articles] |

Re: Q: division vs multiplication kptben@aol.com (1995-04-17) |

Re: Q: division vs multiplication pcg@aber.ac.uk (1995-04-17) |

Re: Q: division vs multiplication gsc@magna.com.au (1995-04-18) |

Re: Q: division vs multiplication jbuck@Synopsys.COM (1995-04-28) |

Re: Q: division vs multiplication davidm@flora.Rational.com (1995-04-28) |

Re: Q: division vs multiplication Roger@natron.demon.co.uk (Roger Barnett) (1995-04-28) |

Re: Q: division vs multiplication jmccarty@spdmail.spd.dsccc.com (1995-04-29) |

Newsgroups: | comp.compilers |

From: | jmccarty@spdmail.spd.dsccc.com (Mike McCarty) |

Keywords: | arithmetic, optimize |

Organization: | DSC Communications Corporation, Plano, Texas USA |

References: | 95-04-080 95-04-135 |

Date: | Sat, 29 Apr 1995 04:47:08 GMT |

<gsc@magna.com.au> wrote:

)martens@cis.ohio-state.edu (Jeff Martens) writes:

)The problem here is that -1 divided by 2 should give -1, with a remainder

)of +1. Unfortunately, it's hard to find hardware that does this right.

By whose definition? I am a mathematician, and I like that definition,

because it makes proving theorems easy. But there are other definitions

which are equally valid. Im some cases, it makes more sense (even to

mathematicians) to have the remainders be negative.

The real problem is, there is no -definitely- best way to define the

quotient and remainder when one or both are negative.

What should (-3)/(-2) be (quotient and remainder)? The answer is, it

depends. It was nice of the ANSI committee to specify the behavior of

div() and ldiv() so we could at least -depend- on the answer being

definite.

Mike

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