Re: floor problems
- To: mathgroup at smc.vnet.net
- Subject: [mg8150] Re: [mg8113] floor problems
- From: Lou Talman <me at talmanl.mscd.edu>
- Date: Sat, 16 Aug 1997 11:50:54 -0400
- Sender: owner-wri-mathgroup at wolfram.com
Tom De Vries wrote: > I had a very frustrating time trying to debug some work I was doing in > Mathematica. I finally pared it down to a problem with the Floor > function, and I have illustrated my concern below. I am using M 3.0 and > a Mac computer. Does anyone have any advice or could you tell me if I > am doing something wrong? > > Floor[(.7 67 10)] > > 469 > > Floor[(67 10 .7)] > > 468 The problem is not with Floor, but with the fact that floating point multiplication of real numbers of fixed length is not, in general, associative: In[1]:= (.7 67 10) - (67 10 .7) Out[1]= \!\(5.68434188608080148`*^-14\) --Lou Talman