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Re: puzzling Octave behaviour
From: |
Francesco Potorti` |
Subject: |
Re: puzzling Octave behaviour |
Date: |
Mon, 24 Jul 2006 10:34:58 +0200 |
>The real problem is that testing doubles for equality doesn't
>work very well. It doesn't have anything to do with Octave, it's
>just a property of the floating point representation that
>computers use. You need to test to see if the numbers are close,
>within some tolerance, like (a - b) < 1e-10, instead of a == b.
You example is wrong, because it should use abs().
Moreover, it assumes that you know the range of values of a and b. For
example, it gives wrong results if a and b are in the order of 1e-10. A
better test would be something like
abs(a-b) < 10*abs(a)*eps
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- puzzling Octave behaviour, Joan Picanyol i Puig, 2006/07/22
- Re: puzzling Octave behaviour, Muthiah Annamalai, 2006/07/22
- Re: puzzling Octave behaviour, Tom Holroyd, 2006/07/22
- Re: puzzling Octave behaviour,
Francesco Potorti` <=
- checking for tiny inequalities (was: Re: puzzling Octave behaviour), Joan Picanyol i Puig, 2006/07/24
- Re: checking for tiny inequalities (was: Re: puzzling Octave behaviour), Bill Denney, 2006/07/24
- Re: checking for tiny inequalities (was: Re: puzzling Octave behaviour), Przemek Klosowski, 2006/07/24
- Re: checking for tiny inequalities (was: Re: puzzling Octave behaviour), Francesco Potorti, 2006/07/24
- Re: checking for tiny inequalities (was: Re: puzzling Octave behaviour), Joan Picanyol i Puig, 2006/07/30