# ?laein

Computes a specified right or left eigenvector of an upper Hessenberg matrix by inverse iteration.

# ?laev2

Computes the eigenvalues and eigenvectors of a 2-by-2 symmetric/Hermitian matrix.

# ?laexc

Swaps adjacent diagonal blocks of a real upper quasi-triangular matrix in Schur canonical form, by an orthogonal similarity transformation.

# ?lag2

Computes the eigenvalues of a 2-by-2 generalized eigenvalue problem, with scaling as necessary to avoid over-/underflow.

# ?lags2

Computes 2-by-2 orthogonal matrices U, V, and Q, and applies them to matrices A and B such that the rows of the transformed A and B are parallel.

# ?lagtf

Computes an LU factorization of a matrix T-λ*I, where T is a general tridiagonal matrix, and λ is a scalar, using partial pivoting with row interchanges.

# ?lagtm

Performs a matrix-matrix product of the form C = `alpha*`A*B+`beta*`C, where A is a tridiagonal matrix, B and C are rectangular matrices, and `alpha` and `beta` are scalars, which may be 0, 1, or -1.

# ?lagts

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.

# ?lagv2

Computes the Generalized Schur factorization of a real 2-by-2 matrix pencil (A,B) where B is upper triangular.

# ?lahqr

Computes the eigenvalues and Schur factorization of an upper Hessenberg matrix, using the double-shift/single-shift QR algorithm.