(MATLAB) Enter the matrix A = [1 2 3 4; 5 6 7 8; 9 10 11 12] (i) Find two-elemen

Question

(MATLAB) Enter the matrix A = [1 2 3 4; 5 6 7 8; 9 10 11 12]

(i) Find two-element arrays I and J such that A(I,J) is a 2 × 2 matrix consisting of the corner elements of A.

(ii) Suppose that B=A initially. Find two-element arrays K and L such that B(:,K) = B(:,L) swaps the first and fourth columns of B.

(iii) Explain the result of C = A(:)

(iv) Study the function RESHAPE. Use it together with the transpose operator .’ in a single (one-line) command to generate the matrix [123456]

                                                                                                                                                                                                                      [ 7 8 9 10 11 12]

from A.

Explanation / Answer

part I:

>> I = [1 3]%first row third row which are edge rows

I =

1 3

>> J = [1 4]%first column 4th column which are edge columns

J =

1 4

>> A(I,J)%first row first column, first row last column, third row first column, third row last column

ans =

1 4
9 12

>>

Part II

K = [1 2 3 4];

L = [4 2 3 1];

>> B(:,K) = B(:,L)

B =

4 2 3 1
8 6 7 5
12 10 11 9

here fourth column placed in first column, 2nd col in 2nd col, 3rd in 2rd and 1st in 4th column

Part III

C(:)

it brings all the elements in single column, column by column

>> C = A(:)

C =

1
5
9
2
6
10
3
7
11
4
8
12

>>

part IV:

reshape(A,m,n)

this function reshapes A into m number of rows and n number of column

we want A of 3 by 4 size matrix into 2 by 6 matrix then

>> reshape(A',[],2)'

ans =

1 2 3 4 5 6
7 8 9 10 11 12

>>

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