Re: Question about Union
- To: mathgroup at smc.vnet.net
- Subject: [mg79231] Re: Question about Union
- From: Bill Rowe <readnewsciv at sbcglobal.net>
- Date: Sat, 21 Jul 2007 04:35:33 -0400 (EDT)
On 7/20/07 at 3:36 AM, yaroslavvb at gmail.com (Yaroslav Bulatov) wrote: >Union treats 2 numbers as distinct even though SameQ returns true >for them...how does it test whether values are distinct by default? >Union[{0.6342350954011774, 0.6342350954011775}] >0.6342350954011774===0.6342350954011775 The problem here isn't with Union but with SameQ. Per the documentation, SameQ returns True when the things being compared are identical. From, In[6]:= data = {0.6342350954011774, 0.6342350954011775}; In[7]:= SameQ @@ data Out[7]= True In[8]:= SameQ @@ (RealDigits /@ data) Out[8]= False it is clear SameQ returns true even when two machine precision numbers are not identical. -- To reply via email subtract one hundred and four