Abstract:The arrangement of Gaussian emission components along a trajectory traced by a visible point moving at non-uniform speed as the pulsar rotates is investigated. By assuming emission locations confined to spots that arranged evenly around the magnetic axis, a Gaussian emission component corresponds to a cut of an emission spot by the trajectory. The distribution of the emission spots, and hence the Gaussian components, are uneven along the trajectory, being highest around the nearest approach of the magnetic axis to the line of sight, and dependent on two angles of a pulsar: the viewing angle, between the rotation axis and the line of sight, and the obliquity angle, between the magnetic and rotation axes. Observed multiple Gaussian components in a profile then corresponds to several emission spots locating on the trajectory within a specific range of pulsar phase. Demonstration is given to show that the number and distribution of the Gaussian components are different between ranges around the near and far sides of pulsar rotation, corresponding to the mainpulse and interpulse, respectively. The total number of emission spots on a trajectory may be different from that around the magnetic axis, and ignoring the motion of the visible point can lead to significant discrepancy in the predicted number of emission spots. The shape and number of the Gaussian components for fitting a profile may be different from that of the actual components that compose the profile. As an example, the model is applied to the emission arrangement in PSR B0826--34 by assuming the emission comes from a single pole.