Symbol and Pi and expressions evaluating to Pi

*To*: mathgroup at smc.vnet.net*Subject*: [mg70117] Symbol and Pi and expressions evaluating to Pi*From*: "David Bakin" <davidbak at gmail.com>*Date*: Wed, 4 Oct 2006 05:59:20 -0400 (EDT)

[I apologize if this question has been asked - as it surely must have been already - my searches didn't get me to the answer in the archives. You can send me some better search terms and I'll be happy with that as an answer, thanks!] The Mathematica 5.1 help browser entry for Symbol under "Further Examples" defines a function SymbolQ1 to determine if something is a Symbol as follows: Attributes[SymbolQ1] = {HoldAllComplete}; SymbolQ1[expr_] := AtomQ@Unevaluated[expr] && Head@Unevaluated[expr]===Symbol Then it shows the following: In:= SymbolQ[Pi] Out= True In:= {a definite integral evaluating to Pi} == Pi Out= True In:= SymbolQ[that definite integral] Out= False Yet FullForm[Pi] is the same as FullForm[that definite integral], and is Pi. So I have two questions: 1) Why isn't SymbolQ[that definite integral] == True? What is it if it isn't a Symbol? 2) Why are FullForm[Pi] and FullForm[that definite integral] different? Thanks! -- Dave

**Follow-Ups**:**Re: Symbol and Pi and expressions evaluating to Pi***From:*Sseziwa Mukasa <mukasa@jeol.com>