[Date Index] [Thread Index] [Author Index]

Re: clearing a variable with a dummy subscript

• To: mathgroup at smc.vnet.net
• Subject: [mg126561] Re: clearing a variable with a dummy subscript
• From: Bill Rowe <readnews at sbcglobal.net>
• Date: Sat, 19 May 2012 05:44:53 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

On 5/18/12 at 5:25 AM, ahautot at ulg.ac.be (Andre Hautot) wrote:

>Hi ! Here is something very simple I don't understand :

>f[x_] := x; f[2]    (*A function*)
>2

>Clear[f]; f[2]       (*The same perfectly cleared as expected*) f[2]
>

>Subscript[u, k_] := k; Subscript[u, 2]        (*u with subscript k_
>entered via the palette*)
>2

>Clear[u]; Subscript[u, 2]          (*I found no way to clear u; a
>suggestion ?) 2

Simply put, Subscript[u,2] is not a symbol (does not have head
Symbol) in Mathematica. Consequently, things designed to work
with symbols often don't work well with Subscript[u,2].

If you want to use Subscript[u,2] or something similar as a
variable your best choice is to load the Notation package. Use
the documentation center to locate the usage guide by searching
on notation package.