Comparison with .49, like N without a second parameter, just uses "machine precision" to evaluate. Since you're playing with values where machine precision doesn't even reach the decimal point, you'll get much worse results than even N[_,0]. In[1]:= x = Abs[FractionalPart[Exp[Pi*Sqrt[163]]] - 1/2]; In[2]:= N[x] Out[2]= -480. In[3]:= N[x,0] Out[3]= 0. In[4]:= N[x,1] Out[4]= 0.5 --Michael On Tue, Apr 1, 2014 at 3:49 PM, Dan Asimov <dasimov@earthlink.net> wrote:
In[44]:= Abs[FractionalPart[Exp[Pi*Sqrt[163]]] - 1/2]
525074825281537487 Sqrt[163] Pi Out[44]= -(------------------) + E 2
In[45]:= N[%,17]
Out[45]= 0.49999999999925007
In[46]:= Abs[FractionalPart[Exp[Pi*Sqrt[163]]] - 1/2] > .49
Out[46]= False
Explanations welcomed.
--Dan _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
-- Forewarned is worth an octopus in the bush.