# Subtract values of a row vector to each column of a matrix.

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Giuseppe on 26 Jul 2018
Answered: Gul Rukh Khan on 8 Dec 2019
Hello guys,
I have written a small code attempting to remove an offset from a set of signals stored in a matrix. I need to subtract for each value of a column of a matrix (120x10) the value contained in a single row vector (1x10). Basically each column of the matrix represents an independent signal.
I have put together some code but I'm not obtaining what expected.
Here 'data' is a matrix (120x10) whereas 'columnMeans' is a row vector (1x10). Each column of the row vector should be used for the subtraction of the corresponding column of the matrix. I'm not even sure whether for loop is necessary.
for i=1:10
data_new=data-columnMeans(i)
end

madhan ravi on 26 Jul 2018
Hi, I have attached an example:
columnMeans=randi([1 10],1 ,10);
data=randi([1 30],120,10);
[m,n] = size(data);
for i=1:m
data_new(i:i,:)=data(i:i,:)-columnMeans(:,:)
end
data_new
size(data_new)

Gul Rukh Khan on 8 Dec 2019
I have another problem, I want to subtract 1st pixel value in 10x10 matrix from the next to the right as well as to the down pixel. and also to store it in r(x,y) matrix. How, I will do it? Please, this command, is not working properly.
for x=1:10
for y=1:10
r (x,y) = (aa(x,y)-(aa(x,y)));
x=x+1;
end
end

R2014a

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