Hello there,

I would like to ask a question regarding an operation on two columns of a matrix as you can see below. Here I proposed two functions to perform the task. The function f1 has two allocations even though I used @view, while the function f2 has no allocation. I am wondering whether it is possible to perform the task with no allocations without using a loop as proposed in function f2? Thanks in advance!

```
f1(x,A,iA,iB) = x .= view(A,:,iA) - view(A,:,iB);
function f2(x,A,iA,iB)
@inbounds @simd for i in 1:size(A,1)
x[i] = A[i,iA] - A[i,iB]
end
end
A = rand(10_000,10_000);
x1 = rand(10_000);
x2 = rand(10_000);
x0 = A[:,6] - A[:,8];
@time f1(x1,A,6,8);
@time f2(x2,A,6,8);
@test x0 ≈ x1
@test x0 ≈ x2
```