[math-fun] just plugging in can be dangerous

z/((z + 1 - Sqrt[2])^2 - 3 + 2*Sqrt[2]) In[689]:= % /. z -> 0 Out[689]= 0 (No 0/0 warning.) In[690]:= Limit[%%, z -> 0] Out[690]= -1/2 - 1/Sqrt[2] This can get much subtler. I'm surprised how rarely it bites us. --rwg