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From: Scott on 28 May 2010 15:28
Debugging a simple program and found that.

Bottom1(l)+0.1<Bottom2(l)
was evaluating as true when Bottom1(l) = -0.4 and Bottom2(l)=-0.3
when I was expecting false as the two halves of the expression should be equal

was also able to get this from the debug line

K>> -0.4+0.1<-0.3

ans =

1

K>> -0.3<-0.3

ans =

0
I'm guessing I'm formatting the expression incorrectly but can't figure out what I'm doing wrong. Thanks for any help
From: Walter Roberson on 28 May 2010 15:39
Scott wrote:

> K>> -0.4+0.1<-0.3
>
> ans =
>
> 1

floating point roundoff error. It's a reality of life, and inescapable in any
finite representation.

http://matlabwiki.mathworks.com/MATLAB_FAQ#Why_is_0.3-0.2-0.1_not_equal_to_zero_.28or_similar.29.3F
From: us on 28 May 2010 16:01
"Scott " <tweedlest(a)remove.this.aol.com> wrote in message <htp5gk$lmj$1(a)fred.mathworks.com>...
> Debugging a simple program and found that.
>
> Bottom1(l)+0.1<Bottom2(l)
> was evaluating as true when Bottom1(l) = -0.4 and Bottom2(l)=-0.3
> when I was expecting false as the two halves of the expression should be equal
>
> was also able to get this from the debug line
>
> K>> -0.4+0.1<-0.3
>
> ans =
>
> 1
>
> K>> -0.3<-0.3
>
> ans =
>
> 0
> I'm guessing I'm formatting the expression incorrectly but can't figure out what I'm doing wrong. Thanks for any help

a hint:
- FP evergreen...

http://matlabwiki.mathworks.com/MATLAB_FAQ#Why_is_0.3-0.2-0.1_not_equal_to_zero_.28or_similar.29.3F

us
From: ImageAnalyst on 28 May 2010 16:04
You may also want to read about "eps" in the help.
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