Index in position 2 exceeds array bounds

I have a problem with this, I dont know whats wrong

n=4;
r= 0.012;
pos = [0 0; 0 0.5; 0.5 0.5; 0.5 0]
a = zeros(1,n)
i=1
while( i<=n)
    for(j=1:1:n-1)
        for(k=1:1:n-1)
            x = pos(k+1,1)-pos(1,j) %%------> I have the problem here

It says "Index in position 2 exceeds array bounds"

Answer 1

[KSSV]

You size of pos is 4x2....you are trying to accessing third coulmn from pos....where as it has only two columns..so obviously you will end up with error.

Answer 2

[Hyeokjin Jho]

Since n = 4, for(j=1:1:n-1) will make j from 1 to 3.

However pos is 4x2 matrix. When j is 3, pos(1,j) refers outside of the matrix boundary.