§2.4纯强迫振动 一、定解问题 u, =a'u+f(r, t)<1> l|=0=0 =0=0§ 2.4 纯强迫振动 一、定解问题 < > < > < > ï î ï í ì = = = + = = 3 2 1 | 0 | 0 ( , ) 0 0 2 t t t tt xx u u u a u f x t