Calculate correlation using mean()

Using the mean() function to calculate numerically the expected value E{·}.

How can I calculate the correlation between two adjacent columns at two time instants?

For example (101, 100).

I have to use mean function(), I'm working with processes

[Adam Danz]

It seems like the problem isn't understood well enough to ask a meaningful question. The mean() is used when computing correlations but it's just one of several steps. The problem has to be clear to you first.

https://www.thoughtco.com/how-to-calculate-the-correlation-coefficient-3126228