k yields four types of equilibria: attractors, saddles of index one and two, and repellors. The collection of these singular solutions is often referred to as the topographic map, molecular map, or phase-space portrait of the function or, more precisely, of its gradient. The phase space between equilibria, or critical points (CPs) of the function, flattens when the relative distance between two or more equilibria decreases. This change in the space curvature can be directly computed via the determinant of the Hessian matrix, |det H|. This matrix, , H is a somewhat arbitrary construct for tabulating the second-order derivatives of a function, i.e.,  =    2 ( , )