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Re: Question from Blind User

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  • Subject: [mg1186] Re: Question from Blind User
  • From: IANC (Ian Collier)
  • Date: Mon, 22 May 1995 01:22:44 -0400
  • Organization: Wolfram Research, Inc.

In article <3pjl8a$7h0 at>, mentat at
(Godshatter) wrote:

>      Just installed the DOS version of Mathematica - the very last copy 
> available, so they told me - and have run up against a problem in the way 
> it displays answers.  If you take the derivative of x^3, it gives the 
> answer as:
>         2
>      3 x
>      If I use a voice synthesyser to read the answer, it will come out as 
> 2 3x.  Using a braille display isn't much better, since I have to 
> remember to look on more than one line for the answer.
>      Is there any way to get the program to display answers in a more 
> Fortran-like method? 
>      3x^2
>  I don't know how useful the program will be for me, if I have to look at 
> multiple lines for the results.  It is feasible to read equations spaced 
> out on paper, but except for some very early arithmetic books, braille 
> math books write equations and expressions one symbol after another.  
> Besides, refreshable braille devices can display only one line at a time, 
> and reading answers that way would involve a lot of extra keystrokes over 
> the course of just a few problems.
>      I would be grateful for any help.  I would think that a program as 
> powerful as Mathematica would allow for this kind of adjustment.  Since 
> the manual is rather large, I have not read it all yet.  If the answer is 
> in the documentation, just point me to it and I'll do the rest.
>      Thanks in advance.
>           Evan Reese
>           mentat at
>      "People are born with legs, not roots."
>           R. Buckminster Fuller 

You can do what you need using $Post, a global variable, which
is applied to every output expression if it is set.

Here is an example of a calculation carried out before and 
after setting $Post to InputForm.

    Integrate[ 1/(x^4 + 1),x]
           -Sqrt[2] + 2 x           Sqrt[2] + 2 x
    ArcTan[--------------]   ArcTan[-------------]
              Sqrt[2]                  Sqrt[2]
    ---------------------- + --------------------- - 
          2 Sqrt[2]                2 Sqrt[2]
                           2                         2
      Log[1 - Sqrt[2] x + x ]   Log[1 + Sqrt[2] x + x ]
      ----------------------- + -----------------------
             4 Sqrt[2]                 4 Sqrt[2]


$Post is a global variable whose value, if set, is applied
   to every output expression.

    $Post = InputForm

    Integrate[ 1/(x^4 + 1),x]
    ArcTan[(-2^(1/2) + 2*x)/2^(1/2)]/(2*2^(1/2)) + 
      ArcTan[(2^(1/2) + 2*x)/2^(1/2)]/(2*2^(1/2)) - 
      Log[1 - 2^(1/2)*x + x^2]/(4*2^(1/2)) + 
      Log[1 + 2^(1/2)*x + x^2]/(4*2^(1/2))

You could apply any other formating that you wished using

I hope this helps.


Ian Collier
Technical Sales Support
Wolfram Research, Inc.
tel:(217)-398-0700     fax:(217)-398-0747      ianc at
Wolfram Research Home Page:   

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