% Solutions # 1
%
% Problem 1
% 
n=3; 

mI=-speye(n,n)
B=sparse(4*diag(ones(1,n))-diag(ones(1,n-1),1)-diag(ones(1,n-1),-1))
D=sparse(diag(ones(1,n)))
UD=sparse(diag(ones(1,n-1),1))
LD=sparse(diag(ones(1,n-1),-1))

A=sparse(kron(D,B))+sparse(kron(UD,mI))+sparse(kron(LD,mI))
