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MathGroup Archive 1998

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RE: Union[{Pi, N[Pi]}]

  • To: mathgroup at smc.vnet.net
  • Subject: [mg12750] RE: [mg12739] Union[{Pi, N[Pi]}]
  • From: Ersek_Ted%PAX1A at mr.nawcad.navy.mil
  • Date: Wed, 10 Jun 1998 03:04:12 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

Mark McClure  wrote:
|
|
|We've seen the Union[{0,0.}] discussion.  Here's a little variation
|which seems a little trickier.
|
|In[8]:=
|N[{3.141592, Pi}, 3] // Union
|
|Out[8]=
|{3.14,3.14}
|
|

In[1]:=
N[{3.141592, Pi}, 3] //InputForm

Out[1]//InputForm=
{3.141592, 3.141592653589793}

You probably expected they would both get rounded to 3 decimal places.
N[expr, 3] gives the same result as N[expr].  At least that's  what I
see  from the lines below.


In[2]:=
x1=N[Pi,3];
x2=N[Pi];


In[3]:=
InputForm[x1]

Out[3]//InputForm=
3.141592653589793


In[4]:=
InputForm[x2]

Out[4]//InputForm=
3.141592653589793


In[5]:=
Precision/@{x1,x2}

Out[5]=
{16,16}


This also explains the other results you reported. _________________
Ted Ersek



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