Re: When Is Precision[ ] $MachinePrecision, And When Is It Not?
- To: mathgroup at smc.vnet.net
- Subject: [mg47580] Re: When Is Precision[ ] $MachinePrecision, And When Is It Not?
- From: drbob at bigfoot.com (Bobby R. Treat)
- Date: Fri, 16 Apr 2004 05:21:26 -0400 (EDT)
- References: <c5dhrd$nqp$1@smc.vnet.net> <c5gg7l$att$1@smc.vnet.net> <c5lfo0$bt2$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Look up == in Help, and you'll find: "SameQ requires exact correspondence between expressions, except that it considers Real numbers equal if their difference is less than the uncertainty of either of them." N[2/3] == 2/3 N[2/3] === 2/3 True False Bobby Harold.Noffke at wpafb.af.mil (Harold Noffke) wrote in message news:<c5lfo0$bt2$1 at smc.vnet.net>... > Bobby: > > Thanks for your examples. I thought about them, and found a very > short one which still bothers me, because the answer is not what I > expected ... > > In[1]:= N[2/3] > > Out[1]= 0.666667 > > In[2]:= N[2/3]==2/3 > > Out[2]= True > > In[3]:= ?== > lhs == rhs returns True if lhs and rhs are identical. > > Regards, > Harold