Vibration frequency response function can be calculated, thereby characterizing the system. This technique is used in the field of experimental modal analysis to determine the vibration characteristics of a structure. The simple mass–spring–damper model is the foundation of vibration analysis, but what about more complex systems? The mass–spring–damper model described above is called a single degree of freedom (SDOF) model since the mass is assumed to only move up and down. In more complex systems, the system must be discretized into more masses that move in more than one direction, adding degrees of freedom. The major concepts of multiple degrees of
Shannon capacity of a graph "α"("G"). The effective number of signals transmitted per unit time step is the "k"th root of this number, "α"("G"). Using these concepts, the Shannon capacity may be defined as the limit (as "k" becomes arbitrarily large) of the effective number of signals per time step of arbitrarily long confusion-free codes. The computational complexity of the Shannon capacity is unknown, and even the value of the Shannon capacity for certain small graphs such as "C" (a cycle graph of seven vertices) remains unknown. A natural approach to this problem would be to compute a finite number of powers of the given