Three-quasiperiodicity, mutual correlations, ordering and long-range modulations in genomic nucleotide sequences for viruses.

Using Fourier transform, we investigate the structural characteristics of genomes for several viruses. The mutual correlations and ordering of the different nucleotides in genomes are compared versus their counterparts from the random sequences with the same nucleotide composition. In order to assess the stastical significance of correlations and ordering we introduce the expression for structural entropy of a sequence and derive the corresponding analytical criteria. The method specially aimed at the investigation of the long-range correlations is described as well and the relationship between the long-range correlations and the modulations of three-quasiperiodicity is discussed.