Re: Defining a function using common notation for absolute value (not Abs[x])

• To: mathgroup at smc.vnet.net
• Subject: [mg112733] Re: Defining a function using common notation for absolute value (not Abs[x])
• From: Albert Retey <awnl at gmx-topmail.de>
• Date: Wed, 29 Sep 2010 04:10:54 -0400 (EDT)

```Am 28.09.2010 12:08, schrieb Gianni:
>
> http://www.accardi.com/tutor/AbsoluteValueNotationSnapShot.bmp
>
> Thanks in advance for any help here.
>
>
> In ASCII:
>
> The given function to work with:  f(x) = (3^-|x|)
>
> Define it in Mathematica:
>
> f[x_]:=3^-Abs[x]
>
> f[x_]:=3^-|x|
>
> Syntax::tsntxi: "|x|" is incomplete; more input is needed.
>
> Syntax::sntxi: Incomplete expression; more input is needed.
>
> I am trying to display the absolute value exponent in the second
> function definition above in the way students will see it in a
> standard math text (with the vertical bars, not Abs, like in the first
> text line).  The first definition above is without error (exponent
> shown as -Abs[x]).  The second is what I am trying to define without
> error.  I am trying to find the button (hopefully on the classroom
> assistant palette) that will produce the desired results.  The button
> in the Typesetting section of the Classroom Assistant won't be
> implemented as an error free function definition as you see in the
> error messages.

I think your best bet is to use TraditionalForm. While I would not
consider it a good choice when generally working with Mathematica, for
the purpose of using it to present your lessions to students it probably
is a reasonable choice. There are two thing you have to do:

1) convert the input cells to traditional form: select the cell and use
corresponding keyboard shortcut, Shift-Ctrl-T on Windows).

2) set the format type for output cells to TraditionalForm in "Edit"
->"Preferences" -> "Evaluation"

you could also set the input format type to TraditionalForm there but I
find it very difficult to create evaluatable input in TraditionalForm,
so I think you will be happier to write standard or input form and the