D = [1 2 3 4 5];
And you want to be able to suck out all entries that are not index i. You can do this with the following:
D(1:end ~= i)
So then the following is produced
i = 1;
D(1:end ~= i)
ans =
2 3 4 5
i = 2;
D(1:end ~= i)
ans =
1 3 4 5
i = 5;
D(1:end ~= i)
ans =
1 2 3 4