DC2 maximum distance algorithm is one of the Identification methods where the mean and standard deviation spectra of the training set spectra are calculated.
The unknown spectra is centered with the mean training spectra and after are divided by the standard deviation spectra, so we get a spectra matrix of the distances.
We can see some high distances for the samples with high difference respect to the mean (samples 1,2 and 3)
After we only have to calculate the maximum value (distance) of this matrix for every row (spectrum)
We can determine a cutoff of 3 by default, but it can be different if needed