Householder Algorithm I have recently started looking at the Householder QR Factorisation and I came across this algorithm. However I am having trouble understanding it . ![enter image description here]( I was hoping someone could explain the second last line on what it does and how it relates to the Householder reflection.

Note that $I - 2v_kv_k^*$ is the Householder reflection associated with $v_k$. We can rewrite that last line as $$ A_{k:m,k:n} = (I - 2v_kv_k^*)A_{k:m,k:n} $$