# Matlab row subtraction of matrix

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Virendra Kowale on 30 Jan 2021
Commented: Paul Hoffrichter on 30 Jan 2021
Matlab subtractions of rows of matrix(eg:- row2-row1) and then how to rewrite the resulatant entire matrix where 2nd row = row2 - row1

Paul Hoffrichter on 30 Jan 2021
On the other hand, maybe you want to subtract row 2 from all the rows. In that case, you can do this.
>> A
A =
1 2 3 4
11 12 13 14
22 23 24 25
42 43 44 45
>> AsubRow2 = A - A(2,:)
AsubRow2 =
-10 -10 -10 -10
0 0 0 0
11 11 11 11
31 31 31 31
Paul Hoffrichter on 30 Jan 2021
But if you wanted to subtract all rows from row 2, then
>> A(2,:) - A
ans =
10 10 10 10
0 0 0 0
-11 -11 -11 -11
-31 -31 -31 -31

Paul Hoffrichter on 30 Jan 2021
I am taking a guess as to what you want. Would be nice if you gave a simple matrix, A, and showed the desired result. But here is my guess about how to subtract adjacent rows.
>> A = [ 1 2 3 4; 11 12 13 14; 22 23 24 25; 42 43 44 45]
A =
1 2 3 4
11 12 13 14
22 23 24 25
42 43 44 45
10 10 10 10
11 11 11 11
20 20 20 20
##### 2 CommentsShowHide 1 older comment
Paul Hoffrichter on 30 Jan 2021
A = [ 1 2 3 4; 11 12 13 14; 22 23 24 25; 42 43 44 45];
B = myFunction(A);
I am not sure what you want. row' = row2 - row1. row' on the left hand side of an = sign is incorrect. Please write down what the values in B should be for the input matrix A.

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