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Re: Zero or not?
From: |
Francesco Potorti` |
Subject: |
Re: Zero or not? |
Date: |
Mon, 23 Jul 2007 11:31:04 +0200 |
>> >Ok, that's a start. If I calculate the sum of N numbers, what is the
>> >maximum 'offset' of the numerical result to mathematically correct
>> >result?
>>
>> Not a numerical expert, but the error magnitude should be bounded by
>> eps*sum(abs(x[1:N])).
>A bound should be like this:
>
> N*eps*max(abs(x))
Ok, more precisely: the sum of two numbers has an error bounded by
2*eps. So, if you sum them starting from the smaller ones you get what
I wrote above. If you sum them without sorting them first, which is
the usual way, you get the second expression that you wrote above.
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- Re: Zero or not?, (continued)
- Re: Zero or not?, Matthias Brennwald, 2007/07/23
- Re: Zero or not?, Francesco Potorti`, 2007/07/23
- Re: Zero or not?, James Sherman Jr., 2007/07/23
- Re: Zero or not?, Miroslaw Kwasniak, 2007/07/23
- Re: Zero or not?, Francesco Potorti`, 2007/07/24
- Re: Zero or not?, kensmith, 2007/07/24
- Re: Zero or not?, Przemek Klosowski, 2007/07/24
- Re: Zero or not?, kensmith, 2007/07/24
- Re: Zero or not?, Francesco Potorti`, 2007/07/22
- Re: Zero or not?, Miroslaw Kwasniak, 2007/07/23
- Re: Zero or not?,
Francesco Potorti` <=
- Re: Zero or not?, kensmith, 2007/07/23
- Re: Zero or not?, Przemek Klosowski, 2007/07/23
- Re: Zero or not?, Robert A. Macy, 2007/07/21
Re: Zero or not?, Bob Weigel, 2007/07/21