Problem with time series analysis function using detrended fluctuation analysis

Hi,

this is quite a specialized question.

I am trying to analyze a time series (standard matrix) using detrended fluctuation analysis. The script/function I am using is dfaedit (see attachment). The problem I am facing is that the results come out negative even though the results are only meant to be positive between 0-2. Hence there must be an issue with the calculation but I can not identify what it is.

Does anyone have an idea?