ICA vector model of microarray gene expression data. Matrix Xdenotes the microarray gene expression data with m genes under n samples or conditions. The columns of A = [a1, a2,..., a
] are the n × n latent vectors of the gene microarray data, where Sdenotes the n × m gene signature matrix or expression mode, in which, the rows of Sare statistically independent to each other. Each gene profile provided x(t) obtained by microarray technology that was considered to be a linear combination of statistically independent components Sthat have specific biological interpretations and latent variables A.