function A=calor2(m,n)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Genera la matriz del calor para una placa bidimensional mxn
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
p=m*n;
v=ones(1,p-1);
for k=n:n:p-1
   v(k)=0;
end
w=ones(1,p-n);
A=4*eye(p)-diag(v,1)-diag(v,-1)-diag(w,n)-diag(w,-n);