matlab程序没错出不来图,matlab程序没报错，图像却出不来

为什么我的程序没报错，图像却出不来？求大佬解惑！

我的代码如下：

close all;

clear all;

L=1; EI=5; T=2; rho=2; M=6;

nt=80000; nx=20; tf=15; Ttr=50;

dx=L/nx; dt=tf/nt;

x = linspace(0,L,nx+1); t_tr = linspace(0,tf,Ttr+1);

w=zeros(nx+1,nt+1);

w3D_free=zeros(Ttr+1,nx+1);

d=zeros(nt+1,1);

for j=1:nt+1

d(j) = 1 + sin(2*pi*(j-1)*dt) + cos(3*pi*(j-1)*dt) ;

end

Br=90;Bl=-90;k=100;k1=1;k2=4;r=1;m=1;

w=zeros(nx+1,nt+1); w3D_model=zeros(Ttr+1,nx+1);

u_model=zeros(nt+1,1);u3D_model=zeros(Ttr+1,1);

ua=zeros(nt+1,1); d_estimate=zeros(nt+1,1);

d1=zeros(nt+1,1);

dbar=max(abs(d));

d_estimate(1:2)= dbar;

for i=1:nx+1

w(i,1)=(i-1)*dx;

w(i,2)=w(i,1);

end

w(1,:)=0;w(2,:)=w(1,:);

w3D_model(1,:)=w(:,1);w3D_model(2,:)=w(:,2);

for j=3:nt+1

for i=3:nx-1

wxx=(w(i+1,j-1)-2*w(i,j-1)+w(i-1,j-1))/dx^2;

wxxxx=(w(i+2,j-1)-4*w(i+1,j-1)+6*w(i,j-1)-4*w(i-1,j-1)+w(i-2,j-1))/dx^4;

w(i,j)=2*w(i,j-1)-w(i,j-2)+(T*wxx-EI*wxxxx)*dt^2/rho;

end

wxl=(w(nx+1,j-1)-w(nx,j-1))/dx;

wxxxl=(w(nx+1,j-1)-3*w(nx,j-1)+3*w(nx-1,j-1)-w(nx-2,j-1))/dx^3;

wxxxtl=(w(nx+1,j-1)-3*w(nx,j-1)+3*w(nx-1,j-1)-w(nx-2,j-1)-w(nx+1,j-2)+3*w(nx,j-2)-3*w(nx-1,j-2)+w(nx-2,j-2))/(dt*dx^3);

wxtl=(w(nx+1,j-1)-w(nx,j-1)-w(nx+1,j-2)+w(nx,j-2))/(dx*dt);

wtl=(w(nx+1,j-1)-w(nx+1,j-2))/dt;

ua(j)=wtl+k1*wxl-k2*wxxxl;

d_estimate(j)= (abs(ua(j))+d_estimate(j-1))/(1+r*dt);

u_model(j)= (-EI*wxxxl+T*wxl-k1*M*wxtl+k2*M*wxxxtl-k*ua(j)-sign(ua(j))*d_estimate(j))/m;

dv=(u_model(j)-u_model(j-1))/dt;

if  dv>0

d0=-m*Br;

else

d0=-m*Bl;

end

d1(j)=d0+d(j);

w(nx+1,j)=2*w(nx+1,j-1) - w(nx+1,j-2) + (m*u_model(j-1)+d1(j-1)+EI*wxxxl-T*wxl)*dt^2/M;

w(nx,j)=(w(nx+1,j)+w(nx-1,j))/2;

if mod(j-1,(nt/Ttr))==0

w3D_model(1+(j-1)*Ttr/nt,:)=w(:,j);

u3D_model(1+(j-1)*Ttr/nt)=u_model(j);

end

end

figure(1);

surf(x,t_tr,w3D_model);

title('Displacement of beam with robust boundary control');

ylabel('Time (s)','Fontsize',12);

xlabel('x(m)','Fontsize',12);

zlabel('w(x,t)(m)','Fontsize',12);

figure(2);

plot(t_tr,u3D_model,'r')

xlabel('time');

ylabel('u');