How to estimate the autocorrelation from nonuniformly spaced data

1. How do you calculate cross correlation and autocorrelation?

How do you calculate cross correlation and autocorrelation?

To detect a level of correlation between two signals we use cross-correlation. It is calculated simply by multiplying and summing two-time series together. In the following example, graphs A and B are cross-correlated but graph C is not correlated to either.