How to calculate the sum of each row in a matrix?

Dear All,

I want to calculate the sum of each row in a large matrix.The matrix looks like:

   y1 y2 y3 y4 y5 
x2 2  4  4  6  7      Sumx2=??
x3 1  2  3  4  5      Sumx3=??
x4 1  2  3  4  5      etc
x5 1  2  4  5  6

My goal is to calculate for each x values the sum of the row. Do you have any idea to do that?

[Jeevith]

how to add a row

Answer 1

[Azzi Abdelmalek]

A=[2  4  4  6  7 
   1  2  3  4  5 
   1  2  3  4  5 
   1  2  4  5  6]
out=sum(A,2)

[afrya]

Ok thanks,so I have to extract the matrix A of my large matrix, because x and y are integer values.Do you know a way that enable to calculate directly the sum of each row, without extracting the matrix A?

[Azzi Abdelmalek]

for example, for row 1

s=sum(A(1,:))

For row n

n=3
s=sum(A(n,:))

You have to read about array

doc array

Answer 2

[Shubham Kumar]

You can create a sum matrix over rows by typing sum(matrixName, 2). This will return an array containing sum over rows.

For more info: http://in.mathworks.com/help/matlab/ref/sum.html

[James Tursa]

This is exactly the same answer that was already given and accepted 1 1/2 years ago.

[Andrew Mccooey]

James Tursa. You're comment is extremely invaluable.

Answer 3

[Delladj Kamel]

You can produce a sum vector over rows of matrix "A" by typing sum(A') where A' is the matrix transpose of matrix "A".

Answer 4

[lurvik pokala]

how to calculate sum of all rows in a matrix given using matlab commands

Answer 5

[loukil sana]

hi, i want to do some controle on the sum of each raw for example: y1 y2 y3 y4 y5 x2 2 4 4 6 7 Sumx2=1000 x3 1 2 3 4 5 Sumx3=1200 x4 1 2 3 4 5 Sumx4=1000 x5 1 2 4 5 6 Sumx5=1200

and i want to note that values given in the matrice are randomly genarating . thanks

Answer 6

[Soumyabrata Bhattacharjee]

I don't know if someone has already highlighted this, I didn't go through all the answers. But coming to your question, you can try this

sum (A')'

where A is the input matrix

[Jan]

This works, but prefer sum(A, 2):

• It saves the time for transposing
• It calculates the wanted sum over the rows also if A is a coulmn matrix. Then the output must equal the input, but with sum(A')' a scalar is replied, because Matlab decides smartly to sum over the column.

[Jaimie Ritchie]

Thank you Jan! That is very helpful. I was able to use this to just find the sum of each row with columns 2 through 4 by using sum(A(:,2:4),2).