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Thread Subject: Very simple number equation does not equate.

Subject: Very simple number equation does not equate.

From: sun

Date: 5 Jul, 2009 15:54:52

Message: 1 of 3

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Dear matlab gurus,

I encountered a very puzzling problem. 0.2+0.2+0.2+0.15+0.05 clearly adds up
to 0.8. But on matlab R2007b, it does not equate. Why? I have been tearing
my hair apart as this problem looks so simple and yet elusive. Could some
matlab guru enlighten a newbie like me?

Below are what appears on my matlab screen;

>> 0.2+0.2+0.2+0.15+0.05==0.8

ans =

     0

>> 0.2+0.2+0.2+0.14+0.06==0.8

ans =

     1

>> 0.2+0.2+0.2+0.2==0.8

ans =

     1

Subject: Very simple number equation does not equate.

From: us

Date: 5 Jul, 2009 15:59:02

Message: 2 of 3

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"sun" <sun@gmail.com> wrote in message <h2qav3$7um$1@reader01.singnet.com.sg>...
> Dear matlab gurus,
>
> I encountered a very puzzling problem. 0.2+0.2+0.2+0.15+0.05 clearly adds up
> to 0.8. But on matlab R2007b, it does not equate. Why? I have been tearing
> my hair apart as this problem looks so simple and yet elusive. Could some
> matlab guru enlighten a newbie like me?
>
> Below are what appears on my matlab screen;
>
> >> 0.2+0.2+0.2+0.15+0.05==0.8
>
> ans =
>
> 0
>
> >> 0.2+0.2+0.2+0.14+0.06==0.8
>
> ans =
>
> 1
>
>
> >> 0.2+0.2+0.2+0.2==0.8
>
> ans =
>
> 1
>

a hint:

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

us

Subject: Very simple number equation does not equate.

From: Matt Fig

Date: 5 Jul, 2009 15:59:03

Message: 3 of 3

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Congratulations! You are the 1 millionth user to find this same floating point "bug" in MATLAB. See the link below.

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

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Tag	Applied By	Date/Time
evergreen	us	5 Jul, 2009 12:04:04
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