Before revision: Superposition of modes Once a set of modes has been calculated for a system, the response at any frequency (within certain bounds) in response to many inputs at many points with different time histories can be calculated by superimposing the result from each mode.
After revision: Superposition of modes Once a set of modes has been calculated for a system, the response at any frequency (within certain bounds) to many inputs at many points with different time histories can be calculated by superimposing the result from each mode.