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need to solve in matlab and please explain. 4 For the matrixes A below, find a f

ID: 2901871 • Letter: N

Question

need to solve in matlab and please explain.

4 For the matrixes A below, find a factorization of A in the form A PCP or A PDP where C is Ta -bl a block-diagonal matrix with 2x2 blocks of the form and D is a diagonal matrix D Consider that the matrices P, C, D have real entries. Discuss your results (why did you obtain one type of factorization or the other, can you obtain both types of factorization for the same matrix) Hint: For each conjugate pair of eigenvalues, use the real and imaginary parts of one eigenvector in C to create two columns of P. Hint: Use the eig command to create the diagonal matrix D and find eigenvectors to create an invertible matrix P. 11 20 17 20 40 -86 -74 a) A 0 -5 10 10 10 28 60 53 T 8 5 -2 0 b) A 2 1 -2 10 8 6-3 3 -2 1 0

Explanation / Answer

a)

A=[7 11 20 17;-20 -40 -86 -74;0 -5 -10 -10; 10 28 60 53];

[P,D]=eig(A);

which gives:

P =

-0.2132 - 0.2132i -0.2132 + 0.2132i        0.3430 - 0.0000i   0.3430 + 0.0000i
   0.8528                         0.8528                  -0.0000 + 0.3430i   -0.0000 - 0.3430i
   0.0000 - 0.0000i     0.0000 + 0.0000i      0.5145 - 0.1715i   0.5145 + 0.1715i
-0.4264 + 0.0000i -0.4264 - 0.0000i            -0.6860           -0.6860        


D =

   2.0000 + 5.0000i        0                             0                              0        
        0                         2.0000 - 5.0000i        0                              0        
        0                         0                             3.0000 + 1.0000i        0        
        0                         0                                   0                         3.0000 - 1.0000i

P inverse

code:

P';

which give

P' =

-0.2132 + 0.2132i   0.8528            0.0000 + 0.0000i -0.4264 - 0.0000i
-0.2132 - 0.2132i   0.8528               0.0000 - 0.0000i -0.4264 + 0.0000i
   0.3430 + 0.0000i -0.0000 - 0.3430i   0.5145 + 0.1715i -0.6860        
   0.3430 - 0.0000i -0.0000 + 0.3430i   0.5145 - 0.1715i   -0.6860

block diagonal factorization:

[P,C] = bdschur(A)

P =

    0.9735    0.2285   -0.3585   -0.2398
    0.2044   -0.8708    0.1021   -0.8419
         0         0              -0.5889    0.0612
   -0.1022    0.4354    0.7171    0.4796


C =

    2.0000     -1.0623         0            0
   23.5345    2.0000          0            0
         0          0                   3.0000    2.3480
         0          0                  -0.4259    3.0000

C is not the block diagonal form mentioned in the question so it cannot be facorized that way

P inverse

code:

P';

which give

P' =

    0.9735    0.2044         0        -0.1022
    0.2285   -0.8708         0         0.4354
   -0.3585    0.1021   -0.5889    0.7171
   -0.2398   -0.8419    0.0612    0.4796

b)

code:

A=[-8 5 -2 0;-5 2 1 -2 ; 10 -8 6 -3 ; 3 -2 1 0];

[P,D]=eig(A)

which gives:

P =

   0.4083 - 0.0000i   0.4083 + 0.0000i   0.4082 - 0.0000i   0.4082 + 0.0000i
   0.8165             0.8165             0.8165             0.8165        
   0.4081 + 0.0001i   0.4081 - 0.0001i   0.4084 + 0.0001i   0.4084 - 0.0001i
-0.0001 + 0.0001i -0.0001 - 0.0001i   0.0001 + 0.0001i   0.0001 - 0.0001i


D =

1.0e-003 *

-0.1878 + 0.1879i        0                  0                  0        
        0            -0.1878 - 0.1879i        0                  0        
        0                  0             0.1878 + 0.1878i        0        
        0                  0                  0             0.1878 - 0.1878i

code:

P'

which give;

P' =

0.4083 + 0.0000i   0.8165             0.4081 - 0.0001i -0.0001 - 0.0001i
   0.4083 - 0.0000i   0.8165             0.4081 + 0.0001i -0.0001 + 0.0001i
   0.4082 + 0.0000i   0.8165             0.4084 - 0.0001i   0.0001 - 0.0001i
   0.4082 - 0.0000i   0.8165             0.4084 + 0.0001i   0.0001 + 0

block diagonal factorization:

code:

[P,C] = bdschur(A)

which gives:

P =

    0.4083   -0.3651    0.4082   -0.7303
    0.8165   -0.1824   -0.0001    0.5477
    0.4081    0.7305   -0.4081   -0.3652
   -0.0001    0.5476    0.8166    0.1826


C =

   -0.0003    1.3425    -4.6668    1.1957
         0         0.0000    1.4904    -16.6676
         0        -0.0000     0.0000    6.7052
         0         0                          0    0.0003

C is not the block diagonal form mentioned in the question so it cannot be facorized that way