An infinitely long cylinder, of radius R, carries a frozen-in magnetisation, parallel to the z-axis, M=k s k-hat, where k is a constant and s is the distance from the axis. there is no free current anywhere. Find the magnetic field B inside and outside the cylinder by using Ampere's law, the loop integral of H.dl=I(subscript enc), to find H, then get B from H=(1/mu0)B-M