In particular, if the data have been over-differenced, the SIACF looks like a SACF from a nonstationary process. The inverse autocorrelation function is not often discussed in textbooks, so a brief ...

Just as any number has an inverse, many functions also have inverses. For example, the inverse of 5 is ⅕. The inverse of the function y = x is y = 1/x.

Just as any number has an inverse, many functions also have inverses. For example, the inverse of 5 is ⅕. The inverse of the function y = x is y = 1/x.

The inverse of a function is a function that links the output value back to the input value. The inverse function for \(f(x)\) is written as \(f^{-1}(x)\).