Re: Noob evaluation question

• To: mathgroup at smc.vnet.net
• Subject: [mg74192] Re: Noob evaluation question
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Wed, 14 Mar 2007 03:44:03 -0500 (EST)
• Organization: The Open University, Milton Keynes, UK
• References: <et54tf\$b7m\$1@smc.vnet.net>

```heycarnut wrote:
> Hi -
>
> Helping a buddy out with a small application, and I'm drawing a blank
> on the following.
>
> Given :
>
>    Position[{1, 2, 3, 4, 5, 6, 7, 8, 9}, _?(# <= Random[Integer, {1,
> 9}] &)]
>
> How can we make the generated random number 'fixed' for the evaluation
> of Position, instead of a new number getting generated at each element
> of the list (the above is a simplified and contrived example.)
>
> Thanks
> Rob
>
>

One must evaluate the random number outside the iterative expression
(the function Position in this case). One way of doing this is,

In[1]:=
With[{rnd = Random[Integer, {1, 9}]},
Print["Generated Random Number : ", rnd];
Position[{1, 2, 3, 4, 5, 6, 7, 8, 9}, _?(#1 <= rnd & )]]

From In[1]:=
Generated Random Number : 7

Out[1]=
{{1}, {2}, {3}, {4}, {5}, {6}, {7}}

Regards,
Jean-Marc

```

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