There are a total of N = 4 K (for DNA sequences) or 20 K (for protein sequences) possible types of K-strings, that is, the strings with fixed length K. We denote the length of a DNA or protein sequence as L. Then a window of length K is used to slide through the sequences by shifting one position at a time to determine the frequencies of each of the N kinds of K-strings in this sequence. We define = ) ... (