find is not matching a value of 1 in an array

I am unable to match a value of 1 with find when checking an array produced by linspace. Is this as expected behavior?

% Create our k samples.

k = linspace(0.1, 2.0, 20)

% Find indexes.

[find(k==0.5) find(k==1.0) find(k==1.5)]

Answer 1

[Adam Danz]

This is due to roundoff error.

Here's a demo showing the roundoff error.

k = linspace(0.1, 2.0, 20);   % 1 is in positon 10
k(10) - 1

ans =
  -1.1102e-16

Here are alternatives.

% find the value of 1
idx = find(ismembertol(k,1)); 

or

% find the value of 1
[~, idx] = min(abs(k-1))

[Jeremy Quandt]

Thank you!

Answer 2

[Loren Shure]

You are running into an issue of floating point arithmetic. You might use ismembertol : mathworks.com/help/matlab/ref/ismembertol.html

[Jeremy Quandt]

Kind thanks :D