slabrd(3) on Linux
The text 44a780c81984, as Debian 4.0 (Etch), Debian 3.1 (Sarge) shipped it.
reduce the first NB rows and columns of a real general m by n matrix A to upper or lower bidiagonal form by an orthogonal transformation Q' * A * P, and returns the matrices X and Y which are needed to apply the transformation to the unreduced part of A