Easy question comparing strings

Hello I have the following code which doesn't work. The problem is Im trying to compare the value "NaN" which I guess isnt a string?...to the value of X. Let me know how to fix it thanks!

 str = input('Please enter a number \n\n','s'); 
 X = str2double(str);
 test=strcmp(X,'NaN');
 if test == 1
    disp('That was not a valid number');
 else
    disp('Here is your number')
    disp(X)
 end

Answer 1

[Tom]

You can just ISNAN instead:

 str = input('Please enter a number \n\n','s'); 
 X = str2double(str);

 if isnan(X)
    disp('That was not a valid number');
 else
    disp('Here is your number')
    disp(X)
 end