why do I have an error on the length function?

hi, I have a file of 70080 lines of which I want to obtain the autocorrelation graph, why do I get this error? I state that previously it worked, can anyone help me?

Also, can anyone give me clues as to what autocorrelation indicates? what is it for?

Answer 1

[Walter Roberson]

You do not have an error on the length function. You have an error on the lenght function.

length  <- what you want
lenght  <- what you have

Answer 2

[Alan Stevens]

You have misspelled length.

[Giuseppe D'Amico]

i solved thanks a lot

Answer 3

[Giuseppe D'Amico]

can you give me theoretical information on autocorrelation?

What are the lags?

[John D'Errico]

Please don't use an answer just to ask another question. This is not even a question about MATLAB anyway.

[Giuseppe D'Amico]

ok, i'm really sorry