How to pick all elements from a set that satisfy a certain condition?

Let's say I have a set of numbers A=-5,-4,-3,-2,-1,0,1,2,3,4,5

and I want to pick those pairs that give a sum of 1. For example, -2 and 3 is one possible pair, but how do we display all such pairs?

Any help will be much appreciated.

Answer 1

[Fangjun Jiang]

A=[-5,-4,-3,-2,-1,0,1,2,3,4,5];
index=(A+A')==1;
[I,J]=find(index);
A([I,J])

ans = 10x2

5 -4 4 -3 3 -2 2 -1 1 0 0 1 -1 2 -2 3 -3 4 -4 5

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