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Re: clearing a variable with a dummy subscript
Posted:
May 20, 2012 2:34 AM


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 > > Thanks in advance, > > ahautot > >
The values of supcripted Variables are not associated with u, but to Subscript:
Subscript[u,2]=123
DownValues[u] returns: {}
DownValues[Subscript] returns: {HoldPattern[u_2]:>123}
So to Clear, you must call:
Clear[Subscript]
(but then *all* subscripted variables are cleared)
 _________________________________________________________________ Peter Breitfeld  Bad Saulgau, Germany  http://www.pBreitfeld.de



