function wtx=psi1fun1(N,t) x=0:0.001:1; a=1; wtx=0; for k=1:N
Bk=2/(k*k*pi*pi)*(cos(3*k*pi/7)-cos(4*k*pi/7)); wtx=wtx+Bk*sin(k*pi*t)*sin(k*pi*x); end （2）
clear
N=4025; dx=0.0024; dt=0.0005; c=dt*dt/dx/dx; x=linspace(0,1,420); u(1:420,1)=0; u(180:240,2)=dt*0.5;
h=plot(x,u(:,1),'linewidth',2); axis([0,1,-1,1]);
set(h,'EraseMode','xor','MarkerSize',18); for k=2:N
set(h,'XData',x,'YData',u(:,2)); drawnow; pause(0.01)
11
u(2:419,3)=2*u(2:419,2)-u(2:419,1)+c*(u(3:420,2)... -2*u(2:419,2)+u(1:418,2)); u(2:419,1)=u(2:419,2); u(2:419,2)=u(2:419,3); end
12