function x = slow(a,b,c)

[m,n] = size(a);

x(1,1) = c(1,1)/(a(1,1)+b(1,1));

for i=1:n,
  x(1,i) = c(1,i);
  for j=1:i-1,
    x(1,i) = x(1,i) - x(1,j)*a(j,i);
  end
  temp = b(1,1)+a(i,i);
  x(1,i) = x(1,i) / temp;
end

for k=2:n,
   for i=1:n,
     x(k,i) = c(k,i);
     for j=1:i-1,
       x(k,i) = x(k,i) - x(k,j)*a(j,i);
     end
     for j=1:k-1,
       x(k,i) = x(k,i) - x(j,i)*b(k,j);
     end
     temp = b(k,k)+a(i,i);
     x(k,i) = x(k,i) / temp;
   end
end

