spbcon(3) on Linux
The text 51f347bf278d, as Debian 4.0 (Etch), Debian 3.1 (Sarge) shipped it.
estimate the reciprocal of the condition number (in the 1-norm) of a real symmetric positive definite band matrix using the Cholesky factorization A = U**T*U or A = L*L**T computed by SPBTRF