clatrd(3) on Linux
The text 7f5bdf48ad8e, as Debian 4.0 (Etch), Debian 3.1 (Sarge) shipped it.
reduce NB rows and columns of a complex Hermitian matrix A to Hermitian tridiagonal form by a unitary similarity transformation Q' * A * Q, and returns the matrices V and W which are needed to apply the transformation to the unreduced part of A