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## Re: strange problem

 From: Mike Miller Subject: Re: strange problem Date: Fri, 28 Nov 2003 02:34:07 -0600 (CST)

```On Fri, 28 Nov 2003, Christoph Dalitz wrote:

> On Thu, 27 Nov 2003 23:03:26 +0000
> Geraint Paul Bevan <address@hidden> wrote:
> > |
> > |    -2.0817e-17    1.0000e+02
> > |    -1.0000e-02    1.0000e+00
> > |
> >
> > The number -2.0817e-17 is -0.000000000000000020817, which is very, very
> > close to zero.
>
> Is there an Octave function that truncates/rounds such small numbers to
> zero (like the Scilab function "clean")?
>
> I have tried "help round" and "help trunc", but found nothing
> appropriate.

Why not use 'round' but first multiply by a large number, then divide by
that same number after round.  For example:

octave:1> x=-2.0817e-17
x =  -2.0817e-17
octave:2> round(x*1e+15)/1e+15
ans = 0

You could write a function that performs that operation on matrices.

Mike

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