1. A method for reducing dimensions of a document vector used to determine the similarity of a first document to a plurality of other documents in a computer, the method comprising: receiving a document that is input to the computer for determining the similarity of the document to the plurality of other documents; preprocessing the document to generate a document vector; reducing a number of dimensions in the document vector, wherein the dimensionality of a document vector d created by the previous process is m and is reduced to a predefined k with dimensions determined by the following equation: d ^ ⁢ : ⁢ ⁢ d ^ = d T ⁢ U k ⁢ ∑ k - 1 , wherein d is an original document vector, U k and Σ k are the matrices resulted from a truncated singular value decomposition (SVD) process and {circumflex over (d)} is the document vector with reduced dimensionality {circumflex over (d)} having k dimensions; comparing the document vector with reduced dimensions to at least one document vector for the plurality of documents to determine a similarity of the document to the plurality of other documents; and displaying a measure of similarity of the document to the other documents to a human observer.