uppose we have a spring with attached mass hanging from the ceiling. The vertical displacement of the mass from its equilibrium (where it sits while at rest) can be modeled by the equation y(t) = et(b cos(t) c sin(t)). One can determine the coefficients , b, c and , by solving a differential equation which incorporates the mass, spring stiffness, friction and so on, or, we can determine these coefficients by studying some data given by its motion