Sum of matrix elements

Lets use this as an example:

I have a matrix A of 5 x 5, and i want a new matrix B of 5 x 1, with the sum of column 2 and 4, of each seperate row.

For example

A = [15, 47, 56, 36, 58; 92, 41, 23, 19, 3; 9, 78, 66, 21, 30; 2, 14, 10, 96, 91; 12, 22, 77, 70, 1]

Then i want B to be B = [47+36; 41+19; 78+21; 14+96; 22+70] B = [83; 60; 99; 110; 92]

[the cyclist]

Royvg94, I have noticed you asking a series of very straightforward questions in this forum, over the course of the last several days. These look very much like homework problems to me. Maybe they are, and maybe they aren't.

If they are, I would just like to caution you. It might seem like you are learning MATLAB this way, but you are not. Even if you feel like, "Oh, now I understand how that works", the learning is simply not the same as figuring it out for yourself.

If these questions are homework, I would encourage you to

• spend more time struggling on them yourself
• clearly identify your questions here as homework problems
• post your code here to get hints, instead of answers

You will find that people here are very willing to help you learn.

[Royvg94]

It's not homework, im using Matlab to analyse data from an experiment I'm running. You got a point that I'll probably find my answers myself, but it would be a huge waste of time, cause I'm not familiar with Matlab.. Im writing a script to analyse these data, and theres just some steps I need to know, which take a lot of time if I would have to figure them out myself, and I have better things to do instead of wasting time on that.

Answer 1

[Andrei Bobrov]

B = sum(A(:,[2,4]),2);