Re: Re: Re: Bug Report - Two numerical values for a same variable
- To: mathgroup at smc.vnet.net
- Subject: [mg54352] Re: [mg54300] Re: [mg54271] Re: Bug Report - Two numerical values for a same variable
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Sat, 19 Feb 2005 02:31:53 -0500 (EST)
- References: <00ed01c512b0$2f242850$6400a8c0@Main> <curpbn$r28$1@smc.vnet.net> <200502150438.XAA29728@smc.vnet.net> <200502161936.OAA19223@smc.vnet.net> <d3d3aacf7f18939828890ce85676bd26@mimuw.edu.pl> <opsmcn3rqciz9bcq@monster>
- Sender: owner-wri-mathgroup at wolfram.com
It has occured to me that it may be a good idea to summarize what (in my opinion) is the situation concering this issue of Complex, Rational, Atoms etc. The following are the two basic Matheamtica principles. 1. All numbers, that is all expressions for which NumberQ returns True are atoms: In[1]:= NumberQ[2/3] AtomQ[2/3] AtomQ[2/3] NumberQ[I] NumberQ[2+I] AtomQ[2+I] Out[1]= True Out[2]= True Out[3]= True Out[4]= True Out[5]= True Out[6]= True 2. Numeric quantities that are not numbers (NumberQ returns False) are Atoms only if they have Head Symbol: In[7]:= NumberQ[Pi+I] AtomQ[Pi+I] Out[7]= False Out[8]= False However In[9]:= NumberQ[Pi] Out[9]= False In[10]:= AtomQ[Pi] Out[10]= True In[11]:= Head[Pi] Out[11]= Symbol Expressions of the form Complex[a,b], Rational[a,b] are only defined where a and b are (certain) numbers. In particular they are not defined for numeric quantities whcih are not numbers, e.g. Complex[Pi,E] and Rational[Pi,Pi] are just undefined expressions. Andrzej Kozlowski
- References:
- Re: Bug Report - Two numerical values for a same variable
- From: Scott Hemphill <hemphill@hemphills.net>
- Re: Re: Bug Report - Two numerical values for a same variable
- From: Murray Eisenberg <murray@math.umass.edu>
- Re: Bug Report - Two numerical values for a same variable