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

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  • Subject: [mg112758] Re: Defining a function using common notation for absolute value (not Abs[x])
  • From: Bill Rowe <readnews at>
  • Date: Wed, 29 Sep 2010 04:15:34 -0400 (EDT)

On 9/28/10 at 6:06 AM, accardi at (Gianni) wrote:

>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]).

I know how I can create a function using Abs where the notebook
will look like I used two vertical bars to create the Abs
function. Basically, I can do this by making use of Traditional
form to get the desired result in an output cell, then doing a
copy paste operation to an input cell to create the function definition.

But while the net effect will be something that looks like a
textbook, it will be very confusing to a new user of
Mathematica. That is, as far as I know there is no simple
obvious way to do this directly from the keyboard.

A somewhat less complex way to create the appearance you want
and have an operational function definition is to write the
function using either InputForm or StandardForm and after entry
is complete convert the input cell to TraditionalForm. This is
something I frequently do when I want to present something to a
colleague for review that is not a Mathematica user and I do not
expect him to actually use what I've done or re-create it in
Mathematica. In this caes, the important thing is to have
notation my colleague is familiar with rather than something he
could easily enter into Mathematica for himself.

>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

The button in the classroom assistant palette and the basic math
input palettes create a template for Abs value using Abs[ ]
rather than two vertical bars

>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.

The button in the typesetting section that does create a
template with two vertical bars simply isn't the Abs function
and won't do what you want.

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