cheub@fmatbpc13:~$ octave
GNU Octave, version 3.2.2
Copyright (C) 2009 John W. Eaton and others.
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octave:1> A=[ 1 9; 0 4; 2 0; 1 0]
A =

   1   9
   0   4
   2   0
   1   0

octave:2> [Q,R]=qr(A)
Q =

  -0.40825  -0.82076  -0.35741  -0.17871
  -0.00000  -0.43774   0.80418   0.40209
  -0.81650   0.32831   0.34297  -0.32852
  -0.40825   0.16415  -0.32852   0.83574

R =

  -2.44949  -3.67423
   0.00000  -9.13783
   0.00000   0.00000
   0.00000   0.00000

octave:3> Q'*Q
ans =

   1.0000e+00  -2.6086e-16  -6.5174e-17  -5.5267e-17
  -2.6086e-16   1.0000e+00   5.9336e-17   3.8787e-17
  -6.5174e-17   5.9336e-17   1.0000e+00  -3.1903e-17
  -5.5267e-17   3.8787e-17  -3.1903e-17   1.0000e+00

octave:4> Q'*Q-eye(4)
ans =

  -3.3307e-16  -2.6086e-16  -6.5174e-17  -5.5267e-17
  -2.6086e-16  -2.2204e-16   5.9336e-17   3.8787e-17
  -6.5174e-17   5.9336e-17   0.0000e+00  -3.1903e-17
  -5.5267e-17   3.8787e-17  -3.1903e-17   0.0000e+00

octave:5> norm(Q'*Q-eye(4),1)
ans =  7.1437e-16
octave:6> Q*R-A
ans =

  -2.2204e-16  -3.5527e-15
   0.0000e+00   0.0000e+00
   0.0000e+00  -1.5673e-15
   0.0000e+00  -8.5446e-16

octave:7> norm(Q*R-A,1)
ans =  5.9745e-15
octave:8> Q(:,1)
ans =

  -0.40825
  -0.00000
  -0.81650
  -0.40825

octave:9> A(:,1)
ans =

   1
   0
   2
   1

octave:10>