What's the difference between nan, NaN and NAN

Question

In numpy there are nan, NaN and NAN. What\'s the sense of having all three, do they differ or any of these can be used interchangeably

Answer 1

Different operating systems and programming languages may have different string representations of NaN:

 nan  
 NaN  
 NaN%  
 NAN  
 NaNQ  
 NaNS  
 qNaN  
 sNaN
 1.#SNAN
 1.#QNAN  
 -1.#IND

I think having all three is just a convenience. They are the same.

>>> np.nan
nan
>>> np.NaN
nan
>>> np.NAN
nan
>>>