# 3.3, Example 2, normal modes U1:=unapply(2*sin(2*Pi*x/5)*cos(2*Pi*100*t/5),(x,t)); plot3d(U1(x,t),x=0..5,t=0..3); U2:=unapply(5*sin(4*Pi*x/5)*cos(4*Pi*100*t/5),(x,t)); U3:=unapply(-7*sin(9*Pi*x/5)*cos(9*Pi*100*t/5),(x,t)); # These are plotted the same way as U1(x,t), see above