Creating a submatrix from a matrix
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Konstantinos
on 4 Dec 2014
Commented: Dyuman Joshi
on 12 Nov 2023
I want a code to create a matrix which consist of rows and columns of another matrix.
i.e. A (4X4) = [ 1 2 3 4; 5 6 7 8; 1 3 5 7; 2 4 6 8; ]
The submatrix B consist of the { 1, 2, 4 }rows of A and the { 2,3 }columns of A:
Β (3Χ2) = [ 2 3; 6 7; 4 6; ]
Any help could be useful.
Thanks in advance!
1 Comment
said mohamed
on 5 May 2021
Using the matrix A = [5 1 11; 7 13 3; 8 5 2], the matrix B is constructed as B = [A A A; A A A; A A A]. Which of the following is the result of the operation K = L * J, made using the submatrices of matrix B, L = B (1: 3,3: 5) and J = B (2: 4,2: 3)?
Accepted Answer
Azzi Abdelmalek
on 4 Dec 2014
Edited: Azzi Abdelmalek
on 4 Dec 2014
A= [ 1 2 3 4; 5 6 7 8; 1 3 5 7; 2 4 6 8; ]
B=A([1 2 4],[2 3])
6 Comments
said mohamed
on 5 May 2021
Using the matrix A = [5 1 11; 7 13 3; 8 5 2], the matrix B is constructed as B = [A A A; A A A; A A A]. Which of the following is the result of the operation K = L * J, made using the submatrices of matrix B, L = B (1: 3,3: 5) and J = B (2: 4,2: 3)?
More Answers (1)
VANSHUL CHOUDHARY
on 20 Aug 2021
A = rand(4,3);
% Get those elements of A that are located in rows 3 to 4 and
% column 2 to 3.
sub_matrix = A(3:4,2:3);
2 Comments
Justin Paulan
on 12 Nov 2023
For example if the matrix is 5x5 and i want to creat a submatrix that is 2x4 it easy to just use how you showed. But i have to creat a submatrix that is 2x4 that has the first 2 rows and columns from the same position in the 5x5 but has the last two rows and columns from the middle position of the 5x5... How do i do that? Matix A is the 5x5 and i wanna get to A4 by using your method.
Dyuman Joshi
on 12 Nov 2023
@Justin Paulan, experiment with the methods shown in the Answers in this thread.
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