A=zeros(100);

A(1,1:10)=1:10;
A(1,11:20)=9:-1:0;

l=0.5;
for i=2:100
   for j=2:99
      A(i,j)=A(i-1,j)+l/2*(A(i-1,j+1)-A(i-1,j-1));
   end
      surf(A);
      pause
end