An idf is frequent for every corpus, and accounts with the ratio of documents that come with the phrase "this". With this case, We've got a corpus of two documents and all of these consist of the phrase "this".log ⁡ N n t = − log ⁡ n t N displaystyle log frac N n_ t =-log frac n_ t N Tf–idf is closely connected to the adverse logarithmicall