# Sum of all odd and even arrays in matrix

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Moe on 29 Oct 2014
Edited: Harry on 30 Oct 2014
Suppose I have a matrix a:
a = [2,3;1,2;1,2;0,1;1,2;3,1;1,3;2,1;2,3;3,1];
I want to build matrix b with dimension 2*2 that first row is sum up of all odd rows of matrix a and second rwo is sum up of all even rows of matrix a
b = [16;19]
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the cyclist on 29 Oct 2014
Here is a hint. Do you know how to make a vector of odd numbers? Even numbers?

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### Accepted Answer

Harry on 29 Oct 2014
Edited: Harry on 30 Oct 2014
From your description, I think you want to do this:
b = [sum(a(1:2:end,:)); sum(a(2:2:end,:))]
However, I'm not sure why you wrote "b = [16;19]". If you want to get that, then just write:
b = sum(a).'
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