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Re: Interesting problem looking for a solution.

  • To: mathgroup at
  • Subject: [mg122082] Re: Interesting problem looking for a solution.
  • From: DrMajorBob <btreat1 at>
  • Date: Wed, 12 Oct 2011 03:44:39 -0400 (EDT)
  • Delivered-to:
  • References: <j6rk1f$1nr$> <>
  • Reply-to: drmajorbob at

He'd also need to know the random number chosen, would he not?


On Tue, 11 Oct 2011 03:25:49 -0500, Murray Eisenberg  
<murray at> wrote:

> With that proposed solution, all the student needs to do to see the
> function's definition is to open the closed cell.
> Very low security!
> On 10/10/11 4:26 AM, Dr. Wolfgang Hintze wrote:
>> "Church, Gary"<churchg at>  schrieb im Newsbeitrag
>> news:j6rk1f$1nr$1 at
>>> Hello,
>>> I have an (I think) interesting problem for you Mathematica gurus.
>>> I'm trying to create a worksheet for my students and want to be able
>>> to display the plot of a randomly generated function f[x], without
>>> them being able to access the expression which defines f; In other
>>> words, I don't want them to be able to evaluate f[x].
>>> The idea is that each student will get a different function f[x] and
>>> will see a different graph and they have to determine the expression
>>> which defines f. They then have to plot the function they think is f
>>> against the actual function f[x] and turn in the two plots (or the
>>> one plot with the two graphs.)
>>> Is this possible?
>>> Thanks much,
>>> Gary
>> Are you looking for something like this?
>> To begin with, define the list lf of possible functions.
>> Then select a definition for f[x] at random from the list, and finally
>> plot it.
>> Repeat the second step (In[219]) as often as you (and your students)
>> like.
>> In[221]:=
>> lf = {x^2, Sin[x], Exp[-x]};
>> In[219]:=
>> f[x_] = lf[[Random[Integer, {1, 2}]]];
>> Plot[f[x], {x, 0, 5}];
>> If you wish to keep the list secret your can hide it from being viewed
>> using the option inspector of the cell (right click>  General
>> Properties>  Cell Open set to false>  Apply).
>> Hope this helps
>> Wolfgang

DrMajorBob at

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