Hello, could someone tell me how to implement this step? A FFT from data in array 1 to array 2. Error here shows ,a2: no such array.

@Leorange You probably created [tabwrite~] before the array. There should be no error when you re-open the patch.
You need to tell [tabread4~] to read.
Then you need to tell [tabwrite~] to write.

David.

@whale-av No, it can not work although I created [tabwrite] after the array [a2].