How do I use if with the value of the array is a string?

I want to check if the final value of the string is 'NaN'

parents=[2 3 1 NaN];
f = parents(size(parents,2));
if f == 'NaN'
    check=0
else
    check=1
end

Answer 1

[per isakson]

Replace

if f == 'NaN'

by

if isnan( f )

[Hang Vu]

Thank you so much! Hope you have a good weekends!