tic;

 clear

 clc

 M=[,,,,,,];%x的步数

 K=M; %时间t的步数

 for p=:length(M)

 hx=/M(p);

 ht=/K(p);

 r=ht/hx^; %网格比

 x=:hx:;

 t=:ht:;

 numerical=zeros(M(p)+,K(p)+);

 numerical(:,)=exp(x); %初始值

 numerical(,:)=exp(t); %边值

 numerical(M(p)+,:)=exp(t+); %边值

 a=-r/*ones(M(p)-,);b=(+r)*ones(M(p)-,);c=-r/*ones(M(p)-,);

 fun1=inline('exp(x+t)','x','t');

 for i=:length(x)

     for j=:length(t)

 Accurate(i,j)=fun1(x(i),t(j));

     end

 end

 d=r/*ones(M(p)-,);e=(-r)*ones(M(p)-,);f=r/*ones(M(p)-,);

 B=diag(d,-)+diag(e,)+diag(f,);

 fun2=inline('','x','t');

 for i=:M(p)-

 for k=:K(p)

     f(i,k)=ht*fun2(x(i+),t(k)+ht/);

 end

 end

 for k=:K(p)

 f(,k)=r/*(numerical(,k+)+numerical(,k));

 f(M(p)-,k)=r/*(numerical(M(p)+,k+)+numerical(M(p)+,k));

 end

 for k=:K(p)

     right_vector=f(:,k)+B*numerical(:M(p),k);

     numerical(:M(p),k+)=chase(a,b,c,right_vector);

 end

 error=numerical(:M(p),:K(p))'-Accurate(2:M(p),2:K(p))';

 error_inf(p)=max(max(error));

 figure(p)

 [X,Y]=meshgrid(x,t);

 subplot(,,)

 mesh(X,Y,Accurate');

 xlabel('x'),ylabel('t');zlabel('Accurate');

 title('the image of Accurate result');

 grid on

 subplot(,,)

 mesh(X,Y,numerical');

 xlabel('x'),ylabel('t');zlabel('numerical');

 title('the image of numerical result');

 grid on

 subplot(,,)

 mesh(X,Y,numerical'-Accurate');

 xlabel('x'),ylabel('t');zlabel('error');

 title('the image of error result');

 grid on

 end

 for k=:length(M)

     H=error_inf(p-)/error_inf(p);

 E_inf(k-)=log2(H);

 end

 figure(length(M)+)

 plot(:length(M)-,E_inf,'-r v');

 ylabel('误差阶数');

 title('Crank nicolson 误差阶数');

 grid on

 toc;