Re: Defining a function using common notation for absolute value (not Abs[x])
- To: mathgroup at smc.vnet.net
- Subject: [mg112762] Re: Defining a function using common notation for absolute value (not Abs[x])
- From: Peter Breitfeld <phbrf at t-online.de>
- Date: Wed, 29 Sep 2010 04:16:18 -0400 (EDT)
- References: <i7ser8$psa$1@smc.vnet.net>
Gianni wrote: > Please refer to: > > 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. > > -------------------------------------------- > At least in StandardForm Mathematica needs opening an closing operators. I did the following to make Abs[x] to be displayed as \[LeftBracketingBar]x\[RightBracketingBar] BracketingBar::usage="\[LeftBracketingBar]x\[RightBracketingBar] is Abs[x] in StandardForm." then I did: MakeExpression[RowBox[{"\[LeftBracketingBar]",x_,"\[RightBracketingBar]"}], StandardForm]:=MakeExpression[RowBox[{"Abs[",x,"]"}],StandardForm] MakeBoxes[Abs[x_],StandardForm]:= RowBox[{"\[LeftBracketingBar]",MakeBoxes[x],"\[RightBracketingBar]"}] I put these settings into my private initialations file, the last two into the Begin["`Private`"] part. Now you can enter Abs[x] and in the Output it shows as |x|. And you can enter Abs[x] as ESC l| ESC x ESC r| ESC If you want to Abs[x] as |x| in the Input Cell use Cell/Convert to StandardForm or the shortcut -- _________________________________________________________________ Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de
