[Rd] typo or stale info in qr man

[Martin Maechler]

>>>>> Wojciech Musial (Voitek) <wojciech.musial at gmail.com>
>>>>>     on Mon, 24 Oct 2016 15:07:55 -0700 writes:

    > man for `qr` says that the function uses LINPACK's DQRDC, while it in
    > fact uses DQRDC2.

which is a modification of LINPACK's DQRDC.

But you are right, and I have added to the help file (and a tiny
bit to the comments in the Fortran source).

When this change was done > 20 years ago, it was still hoped 
that the numerical linear algebra community or more specifically
those behind LAPACK would eventually provide this functionality
with LAPACK (and we would then use that),
but that has never happened according to my knowledge.

Thank you for the 'heads up'.

Martin Maechler
ETH Zurich