# How to use ISNAN function?

425 views (last 30 days)
Shashank on 27 Sep 2012
How to write:
if A(i+2,11) == NaN % Originally posted as: if (i+2,11) == NaN
using ISNAN function?

Matt Fig on 27 Sep 2012
Edited: Matt Fig on 27 Sep 2012
A = [3 nan 4];
isnan(A)
Are you wanting to check whether i+2 or 11 is a nan? Well we know that 11 is not a nan, so let's leave that out. If 'i' is not a nan then i+2 is not a nan. Thus we only have to check on 'i'. Now is 'i' the imaginary unit or are you masking this important MATLAB function by using 'i' as a loop index or other variable? If the latter, then
if isnan(i),disp('i is a nan'),end
By the way, IF statements in MATLAB pass the conditional if ALL of the elements evaluate to true. As you have it, that IF statement would never pass, no matter what 'i' is, because 11 is never a nan. I assume you meant something like:
if [i+2,11] == NaN,disp('In if'),end
Shashank on 27 Sep 2012
Thanks a ton! I think I was making a mistake writing isnan inside the matrix.