either positive-semidefinite nor negative-semidefinite.A symmetric matrix is positive-definite if and only if all its eigenvalues are positive.[26] The table at the right shows two possibilities for 2-by-2 matrices.Allowing as input two different vectors instead yields the bilinear form associated to A:BA (x, y) = xTAy.[27]සංඛ්‍යාත්මක ආකාර[සංස්කරණය]In addition to theoretical knowledge of properties of matrices and their relation to other fields, it is important for practical purposes to perform matrix calculations effectively and precisely. The domain studying these matters is called numerical linear algebra.[28] As with other numerical situations, two main aspects are the complexity of algorithms and their numerical stability. Many problems can be solved by both direct algorithms or iterative approaches. For example, finding eigenvectors can be done by finding a sequence of vectors xn converging to an eigenvector when n tends to infinity.[29]Determining the complexity of an alg