• To: mathgroup at smc.vnet.net
• Subject: [mg53077] Re: Information about subscripted function
• From: Paul Abbott <paul at physics.uwa.edu.au>
• Date: Wed, 22 Dec 2004 04:53:23 -0500 (EST)
• Organization: The University of Western Australia
• References: <cq8tj5\$h18\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```In article <cq8tj5\$h18\$1 at smc.vnet.net>, seb at magda.ifj.edu.pl wrote:

> when I define a function with a subscript in its
> name: (cell content below)
>
> In[1]:= \!\(f\_1[x_] := x^2\)
>
> I can't see it by use of information operator:
>
> In[2]:= \!\(\(?\ f\_1\)\)
>
> Information::ssym
>
> Out[2]:= \!\(Information[f\_1, LongForm -> False]\)
>
> of course I may ask:
>
> In[3]:= ? Subscript
>
> but then I get ALL functions which have subscripts in their names!
>
> so, how to ask about the defintions of subscripted functions ?

By default, the definition is associated with Subscript, not with f. In

Subscript[f, 1][x_] := x^2

and so you can see why this is so.

You could use Symbolize in the

<<Utilities`Notation`

package to symbolize Subscript[f, 1] and then it will work.

Alternatively, you could use association. However, you cannot associate
the definition with f using

f /: Subscript[f, 1][x_] := x^2

However, you can achieve what you want using pure functions:

f /: Subscript[f, 1] := Function[x, x^2]

?f

Cheers,
Paul

--
Paul Abbott                                   Phone: +61 8 6488 2734
School of Physics, M013                         Fax: +61 8 6488 1014
The University of Western Australia      (CRICOS Provider No 00126G)
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Crawley WA 6009                      mailto:paul at physics.uwa.edu.au
AUSTRALIA                            http://physics.uwa.edu.au/~paul

```

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