Re: Mathematica bugs?
- To: mathgroup at smc.vnet.net
- Subject: [mg67317] Re: [mg67301] Mathematica bugs?
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Sun, 18 Jun 2006 05:13:04 -0400 (EDT)
- References: <200606170836.EAA27990@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
On 17 Jun 2006, at 17:36, Yaroslav Bulatov wrote: > When I run the following line > x = Pi/4; For[i = 0, i < 56, i += 1, x = 2*Abs[x - 1/2]]; N[x] > I get > 3. > > But x should always stay between 0 and 1, why do I get 3? > > Also > x = Pi/4; For[i = 0, i < 50, i += 1, x = 2*Abs[x - 1/2]]; N[Log[x]] > gives me > Indeterminate > > How can I get an indeterminate here? > Simply a very usual example of loss of precision due to your using machine precision arithmetic. In[4]:= x = Pi/4; For[i = 0, i < 56, i += 1, x = 2*Abs[x - 1/2]]; N[x,20] Out[4]= 0.79387245267980382900 In[5]:= Pi/4; For[i = 0, i < 50, i += 1, x = 2*Abs[x - 1/2]]; N[Log[x],20] Out[5]= -0.82266639946997263758 No bugs at all. Andrzej Kozlowski
- References:
- Mathematica bugs?
- From: "Yaroslav Bulatov" <yaroslavvb@gmail.com>
- Mathematica bugs?