Computes the RQ factorization of a general rectangular matrix using an unblocked algorithm.
Used by sstedc/dstedc. Merges eigenvalues and deflates secular equation. Used when the original matrix is tridiagonal.
Solves the system of equations (T - lambda*I)*x = y or (T - lambda*I)T*x = y,where T is a general tridiagonal matrix and lambda is a scalar, using the LU factorization computed by ?lagtf.
Returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of an upper Hessenberg matrix.
Computes the (scaled) r-th column of the inverse of the submatrix in rows b1 through bn of tridiagonal matrix.
Provides limited bisection to locate eigenvalues for more accuracy.
Forms the triangular factor T of a block reflector H = I - V*T*VH.
Initializes the off-diagonal elements and the diagonal elements of a matrix to given values.
Computes a partial factorization of a complex Hermitian indefinite matrix, using the bounded Bunch-Kaufman diagonal pivoting method.