The SimilarityCoefficient(s, t) command computes the similarity coefficient of two strings s and t, defined as follows.

Let N(S) denote the set of trigrams of any string S. Then  is the similarity coefficient of s and t, with the convention that strings having no trigrams in common have similarity coefficient equal to infinity.

An optional argument n may be specified causing the similarity coefficient to be computed for n-gram similarity instead of the default trigram similarity.

In typical applications, n is taken to be either  or  (the default). Note that Maple computes this measure as an exact rational quantity, rather than a floating-point approximation. You can obtain a floating-point result by applying evalf to the result.