1. In a system for navigating a document repository in which each document in the document repository comprises at least one segment, a method for computing similarity measurements between various ones of a plurality of segments comprising: populating a matrix representative of the plurality of segments in which each segment of the plurality of segments is represented by keyword frequency data spanning a plurality of keywords, the matrix comprising a plurality of sub-matrices in which each sub-matrix of the plurality of sub-matrices corresponds to a non-overlapping portion of the plurality keywords; for each sub-matrix of the plurality of sub-matrices, calculating a sub-matrix dot product between a first segment of the plurality of segments and a second segment of the plurality of segments, the sub-matrix dot product spanning at least a portion of the non-overlapping portion of the plurality of keywords, to provide a plurality of sub-matrix dot products; and summing the plurality of sub-matrix dot products to provide a similarity measurement between the first segment and the second segment.