slaed4(3) on Linux
The text 901b2f872b8c, as Debian 4.0 (Etch), Debian 3.1 (Sarge) shipped it.
subroutine computes the I-th updated eigenvalue of a symmetric rank-one modification to a diagonal matrix whose elements are given in the array d, and that D(i) < D(j) for i < j and that RHO > 0