MATLAB Central Newsreader - Logical error

Logical error

Andrew — Thu, 22 Oct 2009 14:50:22 -0400

I am getting a logical error with the following code which I don't understand and would appreciate any help figuring out:

>> n=0.6:0.05:2.0;
>> any(n==1.2)

ans =

0

>> any(n==1.0)

ans =

1

I can check all of the values in n and only the value of 1.2 returns false. I would appreciate any help figuring this one out. Thanks.

Re: Logical error

Matt — Thu, 22 Oct 2009 15:41:21 -0400

"Andrew " <apkelley@princeton.edu> wrote in message <hbprfe$lvf$1@fred.mathworks.com>...
> I am getting a logical error with the following code which I don't understand and would appreciate any help figuring out:
>
> >> n=0.6:0.05:2.0;
> >> any(n==1.2)
>
> ans =
>
> 0
>
> >> any(n==1.0)
>
> ans =
>
> 1
>
> I can check all of the values in n and only the value of 1.2 returns false. I would appreciate any help figuring this one out. Thanks.

FAQ. The values of of n are not exact, because there are floating point errors in generating them. It's pure luck that any of them return the expected result.

Re: Logical error

Matt Fig — Thu, 22 Oct 2009 16:04:20 -0400

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