Even though an almost linear system is not exactly a linear system, the portions of the system that are not linear vanish with decreasing distance from the critical point of interest faster than the linear portion vanishes. The linear portion (which can be expressed using a matrix equation with constant coefficients) dominates near the critical point. The cribsheet of linear stability analysis can be used to classify a critical point of an almost linear system with two modifications. If application of linear stability analysis suggests a star or a degenerate node, the shapes of the trajectories should be checked by carefully graphing by hand. If application of linear stability analysis suggests a center, actual trajectories will circulate, but they need to be carefully graphed by hand to determine whether they sink inward, expand outward, or are closed.