Re: Up N' Down values.

*To*: mathgroup at smc.vnet.net*Subject*: [mg13338] Re: [mg13240] Up N' Down values.*From*: David Withoff <withoff>*Date*: Mon, 20 Jul 1998 02:49:57 -0400*Sender*: owner-wri-mathgroup at wolfram.com

> Hi there, > > I'm having some hard time trying to define "up values" to subscripted > variables, what I would like to do is (Latex notations) > > d_1 /: Equal[d_1,0]:=False > > Ok, I know that the full form of d_1 is Subscript[d,1] so I've tried; > > Subscript /: Equal[Subscript[d,1],0]:=Flase > > and > > d /: Equal[Subscript[d,1],0]:=Flase > > but none seems to work, I get the error message: > > TagSetDelayed::"tagnf": "Tag d not found in False==0. > > which I don't understand. > > Any idea? > > Regards. > \/\\/\/\/>> Gadi ORON <<\/\/\/\/ > EMAIL : oron at pmmh.espci.fr > Homepage : http://www.pmmh.espci.fr/~oron/personal.html ICQ#7316619 I would need to see the rest of your input to know what the problem might be. The first input should work fine: In[1]:= Subscript /: Equal[Subscript[d,1],0]:=False In[2]:= Subscript[d,1]==0 Out[2]= False The second input will fail because the symbol d occurs too deeply nested in the left-hand side of the rule: In[1]:= d /: Equal[Subscript[d,1],0]:=False TagSetDelayed::tagpos: Tag d in d == 0 is too deep for an assigned rule to be found. 1 Out[1]= $Failed That's not the message that you reported, however. The message you reported suggests that there must have been some other input. If you had, for example, loaded the Utilities`Notation` package, and used Symbolize to cause the subscripted expression to be treated as a symbol, that would explain the behavior that you reported, since these assignments then amount to trying to attach rules to parts of a symbol, like trying to attach a rule for f1 to f. Dave Withoff Wolfram Research