Autocorrelation

Calculates the autocorrelation of the elements from the intvalue array.

Usage: autocorrelation($<$lag$>$ [,$<$start$>$])

where $<$lag$>$ is the maximum autocorrelation lag that will be computed and [,$<$start$>$] is an optional parameter that specifies the position, in the intvalue array, from which to start calculating the autocorrelation. If this parameter is not specified, the calculation will start from the beginning of the array.