Sample matrix inversion (or direct matrix inversion) is an algorithm that estimates weights of an array (adaptive filter) by replacing the correlation matrix Ru with its estimate. Using K samples x ( k ) , k = 1 , 2 , … , K − 1 {displaystyle x(k),k=1,2,dots ,K-1} , an unbiased estimate of Ru, the correlation matrix of the array signals, may be obtained by means of a simple averaging scheme: Sample matrix inversion (or direct matrix inversion) is an algorithm that estimates weights of an array (adaptive filter) by replacing the correlation matrix Ru with its estimate. Using K samples x ( k ) , k = 1 , 2 , … , K − 1 {displaystyle x(k),k=1,2,dots ,K-1} , an unbiased estimate of Ru, the correlation matrix of the array signals, may be obtained by means of a simple averaging scheme: The expression of the theoretically optimal weights requires the inverse of Ru, and the inverse of the estimates matrix is then used for finding estimated optimal weights.