How to concatenate matrices
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jake stan
le 2 Mar 2018
Modifié(e) : Pawel Jastrzebski
le 2 Mar 2018
Create a 4x4 magic matrix A. Use MATLAB to assemble a new matrix B. I'm not sure how to turn the 4x4 matrix A in to a 2x2 matrix B, where first row: A 2A, second row: A^2 A+2
A = magic(4)
B = [A 2A; A.^2 A+2]
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Pawel Jastrzebski
le 2 Mar 2018
You must have got an error message when executing - what did it say? That should be your first clue as to what's wrong with the code.
In your case, the multiplication sign is missing '*'.
A = magic(4)
B = [A 2*A; A.^2 A+2]
Output:
>> B
B =
16 2 3 13 32 4 6 26
5 11 10 8 10 22 20 16
9 7 6 12 18 14 12 24
4 14 15 1 8 28 30 2
256 4 9 169 18 4 5 15
25 121 100 64 7 13 12 10
81 49 36 144 11 9 8 14
16 196 225 1 6 16 17 3
3 commentaires
Pawel Jastrzebski
le 2 Mar 2018
Modifié(e) : Pawel Jastrzebski
le 2 Mar 2018
"." means it's an 'element-wise' operation. You need to have two matrices of the same size and the respective elements in them will be multiplied/divied/raised to the power.
If you ommit the "." it's considered as a normal matrix operation.
Jan
le 2 Mar 2018
@jake stan: A.^2 squares the elements of the array A, while A^2 calculates A*A with the matrix multiplication.
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