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Sum of the elements of rows of matrix

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Akmyrat
Akmyrat on 28 May 2014
Commented: Jos (10584) on 29 May 2014
lets say i have A=[1 2 1;3 2 1;3 5 4] and i want to sum up row elements separately and show me results as "Ri=..." here "i" is number of row. in this case R1=7, R2=9. R3=6.

  1 Comment

Matt J
Matt J on 28 May 2014
It sounds like you really mean "sum up column elements". The elements you are summing all belong to a common column, not a common row.

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Accepted Answer

Matt J
Matt J on 28 May 2014
Edited: Matt J on 28 May 2014
Asum=sum(A,1);
for i=1:length(Asum)
disp(['R' num2str(i) '=' num2str(Asum(i))]);
end

  4 Comments

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Jos (10584)
Jos (10584) on 28 May 2014
This code hurts, Matt J ;-)
Matt J
Matt J on 28 May 2014
Hurts in what way? As you recommended, I do not autogenerate separate variables R1, R2, R3,...
Jos (10584)
Jos (10584) on 29 May 2014
:-) Indeed, you exactly did what Akmyrat asked for ...

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More Answers (2)

Chandrasekhar
Chandrasekhar on 28 May 2014
sum(A')

  2 Comments

Matt J
Matt J on 28 May 2014
This won't work if A is a row vector. Transposing is also expensive in computation time and memory if A is large.
Chandrasekhar
Chandrasekhar on 28 May 2014
Please let us know what is best way to do this?

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Jos (10584)
Jos (10584) on 28 May 2014
You do not want to store the results in separate variables R1, R2, etc., but rather as elements of a single variable R, with R(1), R(2), etc.
A = magic(3)
RowSum = sum(R,2)
help sum

  2 Comments

Akmyrat
Akmyrat on 28 May 2014
Hi jos, thanks. but sorry your code also not working.
Jos (10584)
Jos (10584) on 28 May 2014
What do you mean, "not working"? Did you read the help of sum?
May be you want to sum along rows rows, i.e., sum the elements in each column?
ColumnSum = sum(R,1)
Next time, be a little bit more specific ...

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