why is NaN not of 'NaN type' in Simulink?

Hi everyone,

Please, could anyone explain why the constant block NaN is not of type NaN?

Thank you in advance!

Best regards,

Nicolas

[Nicolas CRETIN]

To solve the problem I first converted my input into a string and then I applied a string comparison:

But this is still a weird behaviour

Answer 1

[Paul]

It looks like the block labeled "assertion1" is a Compare To Constant block.

Instead use a Relational Operator block, which supports isNaN functionality.

[Nicolas CRETIN]

Oh, right thank you!

Answer 2

[Steven Lord]

By the definition of NaN, NaN is not equal to anything (including itself.) This is documented on the documentation pages for the NaN function as well as the documentation page for the == operator.

If you can call MATLAB functions in your model, use isequaln to perform equality testing including treating NaN as equal to NaN.

x = NaN;
x == x % false

ans = logical
   0

isequal(x, x) % false

ans = logical
   0

isequaln(x, x) % true

ans = logical
   1

[Nicolas CRETIN]

Thanks a lot!