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From: | Jules Bean | Date: | April 21 1999 9:39am |

Subject: | Re: bc math support in MySQL? | ||

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On Wed, 21 Apr 1999, Tobias Rischer wrote: > > On fixed point numbers, it was said that: > > > Essentially, this should be implemented simply as an integer, with an > > automatic scale on the IO routines. > > > > Alternatively, simply use an integer, and do the scaling in your > > middleware! ;) > > Just to keep people from stumbling, I'd like to add: > > This is good advice, as long as the only calculations done on the > integers *as integers* (e.g. in a SELECT expression) are + and - > operations. It will wonderfully fail for "<fixed> * <fixed>" or > "<fixed> / <fixed>"; these operations need to know about the implied > scaling. > > It is ok to do "<int> * <fixed>", "<fixed> / <int>" etc. > > Tobias > > > Personal Statement: > > I like the idea of fixed point numbers as the underlying data type for > DECIMAL(m,n) [or was it NUMERIC?], maybe even a BCD type. I can't think of any advantages to BCD at all.. someone enlighten me.. > > I'm not much of a business man, but even I wouldn't like my bank to > arbitrarily toggle the last digits of my bank account and explain that > with floating point anomalies caused by the exact sequence of my earning > and spending money. (I can almost see them telling me I should never > look for exact equality in an account balance, but rather use some > appropriate Epsilon! :-) Yup. The appropriate epsilon is one half of a cent, in general. Someone told me (I can't substantiate this myself) that most bank accounts automatically round to the nearest penny/yen/pfennig at the close of business each day. Jules /----------------+-------------------------------+---------------------\ | Jelibean aka | jules@stripped| 6 Evelyn Rd | | Jules aka | jules@stripped| Richmond, Surrey | | Julian Bean | jmlb2@stripped| TW9 2TF *UK* | +----------------+-------------------------------+---------------------+ | War doesn't demonstrate who's right... just who's left. | | When privacy is outlawed... only the outlaws have privacy. | \----------------------------------------------------------------------/

Thread | ||
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• bc math support in MySQL? | jkraai | 20 Apr |

• Re: bc math support in MySQL? | Jules Bean | 20 Apr |

• Re: bc math support in MySQL? | Tobias Rischer | 21 Apr |

• Re: bc math support in MySQL? | Tobias Rischer | 21 Apr |

• Re: bc math support in MySQL? | Tobias Rischer | 21 Apr |

• Re: bc math support in MySQL? | Jules Bean | 21 Apr |

• Re: bc math support in MySQL? | Fred Read | 21 Apr |

• Re: bc math support in MySQL? | jkraai | 20 Apr |