A wave packet is a localized disturbance that results from the sum of many different wave forms. If the packet is strongly localized, more frequencies are needed to allow the constructive superposition in the region of localization and destructive superposition outside the region. From the basic solutions in one dimension, a general form of a wave packet can be expressed as u ( x , t ) = 1 2 π π ∫ ∫ − − ∞ ∞ ∞ ∞ A ( k ) e i ( k x − − ω ω ( k ) t ) d k .