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
Oh Dear! What Can the Matter Be? basin it was the same water the next washed her face in – and nobody knew they were there. </poem> "Seven Old Ladies" was not the first parody, however. Long before that parody, the song had been parodied for political purposes. One such parody can be found in the "Wisconsin State Journal" of 1 March 1864. It was written to exhort parents, who during the U.S. Civil War had not taken much interest in public schooling in Madison, to visit the schools of their children. Its lyrics were: <poem> Oh, dear, what can the matter be? Oh, dear, what can