How would we find the lower bound and and separate bounds on vector components?
For the lower bound, you need to start from Ax = b and r = b - Ax,
and work out details to A(x-xhat) = r. From there, using norm properties,
you can get the lower bound.
For the separate (not necessarily very sharp) bounds, you only need to know the inf norm definition.
1 Like
Once we have A(x-xhat) = r, can’t we get the exact value for the norm of x-xhat?
I don’t see how.