Regular matrix may refer to: Mathematics Regular stochastic matrix, a stochastic matrix such that all the entries of some power of the matrix are positive The opposite of irregular matrix, a matrix with a different number of entries in each row Regular Hadamard matrix, a Hadamard matrix whose row and column sums are all equal A regular element of a Lie algebra, when the Lie algebra is gln Invertible matrix (this usage is rare) Other uses QS Regular Matrix, a quadraphonic sound system developed by Sansui Electric