例6- 40 求矩陣A的正交分解。
解：在命令窗口中輸入如下命令，并按Enter鍵確認。
>>  A=[13 4 7;3 8 9;5 7 11]
A =
    13     4     7
     3     8     9
     5     7    11
>>  [Q,R]=qr(A)
Q =
   -0.9124    0.3761   -0.1614
   -0.2106   -0.7695   -0.6030
   -0.3509   -0.5162    0.7813
R =
  -14.2478   -7.7907  -12.1422
         0   -8.2647   -9.9706
         0         0    2.0381
>>  [Q,R,E]=qr(A)
Q =
   -0.4418    0.8933   -0.0828
   -0.5681   -0.3500   -0.7448
   -0.6943   -0.2821    0.6621
R =
  -15.8430  -10.9197  -11.1721
         0    9.1521   -1.2015
         0         0   -1.6552
E =
     0     1     0
     0     0     1
     1     0     0
>> [Q,R]=qr(A,0)
Q =
   -0.9124    0.3761   -0.1614
   -0.2106   -0.7695   -0.6030
   -0.3509   -0.5162    0.7813
R =
  -14.2478   -7.7907  -12.1422
         0   -8.2647   -9.9706
         0         0    2.0381
>>  R=qr(A)
R =
  -14.2478   -7.7907  -12.1422
    0.1101   -8.2647   -9.9706
    0.1835    0.3231    2.0381
>>