Re: (2/3)[[1]]
- To: mathgroup at smc.vnet.net
- Subject: [mg96402] Re: (2/3)[[1]]
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Fri, 13 Feb 2009 03:40:05 -0500 (EST)
- Organization: The Open University, Milton Keynes, UK
- References: <gn11e8$7vn$1@smc.vnet.net>
In article <gn11e8$7vn$1 at smc.vnet.net>, obott0 at gmail.com wrote: > I'm not sure if this has been asked before, but why can't Part be used > with Rational? > > i.e. (2/3)[[1]] Because even if rational numbers look like non-atomic expressions (see, for instance, their full or tree forms), they are deemed by Mathematica as *atomic* expressions (test with *AtomQ[]*). In[1]:= (2/3)[[1]] During evaluation of In[1]:= Part::partd: Part specification (2/3)[[1]] is longer than depth of object. >> Out[1]= 2 (-)[[1]] 3 In[2]:= FullForm[2/3] Out[2]//FullForm= Rational[2, 3] In[3]:= %[[1]] During evaluation of In[3]:= Part::partd: Part specification (2/3)[[1]] is longer than depth of object. >> Out[3]= 2 (-)[[1]] 3 In[4]:= TreeForm[2/3] Out[4]//TreeForm= -Graphics- In[5]:= AtomQ[2/3] Out[5]= True Regards, --Jean-Marc