if uplo = 'L', 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 of A is zeroed.
if uplo = 'U', 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 of A is zeroed.
if uplo = 'L', 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 of A is zeroed. if uplo = 'U', 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 of A is zeroed.