Re: Zero or not?

[Matthias Brennwald]

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? I'd guess its N*eps, but I'm not sure.

Matthias



On 21.07.2007, at 19:14, Ben Abbott wrote:

> check out the function "eps"
>
> On Jul 21, 2007, at 12:45 PM, Matthias Brennwald wrote:
>
> > Ok. Is there a way to predict the expected offset? I need to test if
> > the sums across the columns of a matrix are zero, or at least within
> > the bounds expected from the IEEE arithmetic.
> >
> > Matthias
> >
> > On 21.07.2007, at 15:17, Jordi Gutiérrez Hermoso wrote:
> >
> > > On 21/07/07, Matthias Brennwald <address@hidden> wrote:
> > > > I expected the below code to yield only zeros, but it does not:
> > >
> > > That's just the way IEEE arithmetic works. When subtracting two
> > > numbers that are very close, you may not get zero, just machine
> > > epsilon. Try this, for fun: 0.3 - 0.2 - 0.1
> > >
> > > - Jordi G. H.




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