Colon operator numerical error

When I create a vector using the colon operator I noticed for certain vectors there is a small numerical error in the values returned. For example: >> a = 0:.1:1

a =

            0          0.1          0.2          0.3          0.4          0.5          0.6          0.7          0.8          0.9            1

>> a(4)

ans =

          0.3

>> a(4) == .3

ans =

     0

>> a(4) - .3

ans =

   5.5511e-17

I find this very strange. Do other people have this same problem?

Answer 1

[Walter Roberson]

Yes, everyone has this problem. Please read this FAQ

[Rowland]

Good to know. Thanks!

[Jan]

To be exact: I have the same *behaviour*, which is caused by the underlying representation of numbers. A *problem* occurs only, if a user has not matching expectations.