in crates/ratchet-core/src/ops/norm/mod.rs [327:337]
fn kernel_element(&self, dst: &Tensor) -> KernelElement {
let rank = dst.rank();
let N = dst.shape()[rank - 1] as u32;
if N % 4 == 0 {
KernelElement::Vec4
} else if N % 2 == 0 {
KernelElement::Vec2
} else {
KernelElement::Scalar
}
}