Just for my clarification: A comparison of two identical strings should always yield a 1.0 as result, correct? string s1 = "hello world"; string s2 = "hello world"; double x = s1.RatcliffObershelpSimilarity(s2); -> x = 0.7272727272 Also, I was trying to get the same numbers like on this page for reference checking: https://itnext.io/string-similarity-the-basic-know-your-algorithms-guide-3de3d7346227 But already the first example differs: string1, string2 = "i am going home", "gone home" textdistance.ratcliff_obershelp(string1, string2) 0.66 Your extension: 0.58333333 string1, string2 = "test", "text" textdistance.ratcliff_obershelp(string1, string2) 0.75 Your extension: 0.5 Am I using the extension wrong or is there a problem with the implementation?