  qr
  Builtin Function



      SSyynnooppssiiss
        QR decomposition

      SSyynnttaaxx
        qr ( _A )

        qr ( _A, "p" )

      DDeessccrriippttiioonn

        Qr computes the QR decomposition of the input matrix A such
        that:


          A = Q * R


     or


          A*p = Q * R


     Qr returns a list containing elements _q and _r. Optionally, qr can
     take a second argument, "p" which tells qr to perform column
     pivoting when computing _q and _r. The permutation matrix _p is
     returned in the same list as _q and _r.

     Qr utilizes LAPACK subroutines DGEQRF and DORGQR for REAL inputs,
     and ZGEQRF and ZUNGQR for COMPLEX inputs. When column pivoting is
     requested the LAPACK subroutines DGEQPF, and ZGEQPF are used.






























