Re: clearing a variable with a dummy subscript

*To*: mathgroup at smc.vnet.net*Subject*: [mg126557] Re: clearing a variable with a dummy subscript*From*: Bob Hanlon <hanlonr357 at gmail.com>*Date*: Sat, 19 May 2012 05:43:30 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201205180925.FAA17125@smc.vnet.net>

Subscript[u, k_] := k Subscript[u, 2] 2 This assignment is associated with Subscript rather than with u You would need to clear Subscript. Clear[Subscript] Subscript[u, 2] Subscript[u, 2] However, if you had made multiple assignments with Subscript this would clear all of them rather than just u To associate the assignment with just u, use an upvalue (see help for UpValues, UpSet, UpSetDelayed) u /: Subscript[u, k_] := k Subscript[u, 2] 2 Now Clear will work as you intended Clear[u]; Subscript[u, 2] Subscript[u, 2] Bob Hanlon On Fri, May 18, 2012 at 5:25 AM, Andre Hautot <ahautot at ulg.ac.be> 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 subscrip= t k_ > entered via the palette*) > 2 > > Clear[u]; Subscript[u, 2] (*I found no way to clear u;= a > suggestion ?) > 2 > > Thanks in advance, > > ahautot >

**References**:**clearing a variable with a dummy subscript***From:*Andre Hautot <ahautot@ulg.ac.be>