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Re: machine accuracy

by Maclir (Curate)
on Jun 18, 2003 at 12:43 UTC ( #266802=note: print w/ replies, xml ) Need Help??


in reply to machine accuracy

Are you concerned about accuracy or precision? In general, accuracy is "how close to the correct value is my answer", while precision is "how many significant digits does my answer contain."

What you are describing is precision - and as someone else mentioned, bignum could be your friend. However, once you start manipulating high precision values, you need to make sure your numerical methods do not reduce your accuracy. In the dim, dark past, I did an honours-level university applied math subject that dealt with how to structure calculations so that numerical rounding errors did not accumulate and destroy your accuracy. Sadly, I have forgotten much of it!


Comment on Re: machine accuracy
Re: Re: machine accuracy
by maksl (Pilgrim) on Jun 18, 2003 at 16:18 UTC
    thx Maclir for clarifying the definitions.
    i'm interested as the title and the little formula indicates in the accuracy, which as physician i would describe in analogy to a statistical random walk depending on the square root of how many times you walk(multiplicate) multiplicated with the inevitable machine inaccuracy.
    "how close to the correct value is my answer" permits some level of trust to the data, doesn't it?
    but please tell more if you can dig up :)

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