S r(x,y, z, t)v(x,y, z, t) a s F'(x,y, z, t") v(,y, z',t) 正变换逆变换 s tyS u x'=x-ut x=x'tut P y=y XX 2三2 r=r+oo正变换 x  = x −ut y  = y z  = z t = t 逆变换 t t z z y y x x ut =  =  =  =  +  S S r(x, y,z,t)  r (x  , y  ,z  ,t)  v(x, y,z,t)  v (x  , y  ,z  ,t)  a  a   P r  o  S u x  o x y S r   y  r r oo    = + 