Re: beauty or accuracy
- To: mathgroup at smc.vnet.net
- Subject: [mg103882] Re: beauty or accuracy
- From: Bill Rowe <readnews at sbcglobal.net>
- Date: Sat, 10 Oct 2009 07:10:18 -0400 (EDT)
On 10/9/09 at 7:18 AM, zhengji.li at gmail.com (Li Zhengji) wrote: >Hi all, > >42500 - 1907.25 = 40592.8 >(http://www.wolframalpha.com/input/?i=42500+-+1907.25) >I do believe that it is because Mathematica "thinks" it's *better* >to limit the result to six digits, so 0.75 is rounded to 0.8. >But, don't you think that the result is a little strange, or >inaccurate? Not at all. By default Mathematica *displays* machine precision numbers as being only 6 digits. But the actual value used by Mathematica has more digits. That is In[1]:= x = 42500 - 1907.25 Out[1]= 40592.8 In[2]:= RealDigits[x] Out[2]= {{4,0,5,9,2,7,5,0,0,0,0,0,0,0,0,0},5}