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Topic: clearing a variable with a dummy subscript
Replies: 5   Last Post: May 21, 2012 5:59 AM

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Bill Rowe

Posts: 1,647
Registered: 3/14/08
Re: clearing a variable with a dummy subscript
Posted: May 19, 2012 5:47 AM
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On 5/18/12 at 5:25 AM, (Andre Hautot) wrote:

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

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

>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*)

>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.

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