MATLAB编程求解二维泊松方程(共3页).doc

% 真解 u=sin(pi*x)*sin(pi*y) % 方程 -Laplace(u)=f % f=2*pi2*sin(pi*x)*sin(pi*y) %difference code for elliptic equations with constant coefficient %clear all%clcN=20;h=1/N;S=h2;x=0:h:1;y=0:h:1;% Stiff matrix A=zeros(N-1)2,(N-1)2);for i=1 A(i,i)=4/h2; A(i,i+1)=-1/h2; A(i,i+(N-1)=-1/h2;endfor i=N-1 A(i,i-1)=-1/h2; A(i,i)=4/h2; A(i,2*i)=-1/h2; %A(i,i+(N-1)=-1/h2endfor i=(N-2)*(N-1)+1 A(i,i-(N-1)=