IdFt typedef Null safety

IdFt = double

Alias for double where it represents the inverse document frequency of a term.

IdFt is defined as idft = log (N / dft), where:

  • N is the total number of terms in the index;
  • dft is the document frequency of the term (number of documents that contain the term). The IdFt of a rare term is high, whereas the IdFt of a frequent term is likely to be low.

Implementation

typedef IdFt = double;