Lorentz factor in the observer frame (solid lines) and in the comoving frame (dashed lines) in the left-hand panel, and the relative error in the comoving Lorentz factor in the right-hand panel for ﹩\kappa =100﹩. The error for the Boris scheme and the HC scheme overlap in the right-hand panel and are indistinguishable. The error in the gyroradius ﹩{R}_{c}=m\gamma ^{\prime} {v}_{\perp }/q| B^{\prime} | ﹩ in the right-hand panel of Figure 8 can be directly related to the difference in the evolution of γ in the left-hand panel of this figure and to the error in γ in the right-hand panel of this figure.