Adding 3 numbers out of 5

Hi,

I am trying to do a code for channel interference. I figured out everything else but I'm stuck at a few points.

I have 5 numbers stored under different names, A,B,C,D,E.

I want to take three at a time and add them together for example: A+B+C. I want matlab to do all the combinations. Is that possible? can you tell me how?

Thank you.

Answer 1

[Mischa Kim]

Sarah, you could use

 data    = [A B C D E];
 datasum = sum(combnk(data,3),2);

[MatlabGirl]

Man! This is awesome! Thank you thank you thank you!

1) Is there another function for subtraction too. A-B-C (for the different combination) 2) What about a mix of sum and add? like A-B+C.

Thank a lot.

[Mischa Kim]

Sure.

 datadif  = sum(combnk(data,3)*[1 -1 -1]',2)

With the column vector, e.g. [1 -1 -1]', you can control the signs.

[MatlabGirl]

Thanks a lot! I can't thank you enough!