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Re: Two-dimensional input

  • To: mathgroup at
  • Subject: [mg31564] Re: [mg31183] Two-dimensional input
  • From: Omega Consulting <omega_consulting at>
  • Date: Sun, 11 Nov 2001 16:26:07 -0500 (EST)
  • Sender: owner-wri-mathgroup at

At 11:19 PM 10/15/2001, Garry Helzer wrote:
>To accompany some lecture notes I am developing I would like to define a
>pair of functions of x that could be entered from the keyboard as
>x^\[UpArrow] and x^\[DownArrow]. The problem is that \[UpArrow] is a
>binary operator and \[DownArrow] is a letterlike form. Is there a way? I
>could, of course, use something like superminus and subminus, but I really
>prefer the arrows.

To have a certain kind of input interpreted as an expression, you must 
define how to convert the boxes into that expression. For example,

In[]:= MakeExpression[SuperscriptBox["x","\[UpArrow]"],form_] :=

In[]:= \!\(\(x\^\[UpArrow]\)[1]\)
Out[]= XUpArrow[1]

If you want output to use the special form, you must define how to turn an 
expression into boxes.

In[]:= MakeBoxes[XUpArrow[arg_], form_] :=
   RowBox[{SuperscriptBox["x","\[UpArrow]"], "[",MakeBoxes[arg],"]"}]

In[]:= \!\(\(x\^\[UpArrow]\)[1]\)
Out[]= \!\(\(x\^\[UpArrow]\)[1]\)

Omega Consulting
"The final answer to your Mathematica needs"

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