Return solves a system of linear equations \A * X = B, using Cholesky factorization.
if uplo = Lower, the leading 'N x N' lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part if A is not referenced. if uplo = Upper, the leading 'N x N' upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part if A is not referenced.
If uplo = 'L': lower triangle of 'matrix' is stored. If uplo = 'U': upper triangle of 'matrix' is stored.