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.