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Re: while loop through a list

  • To: mathgroup at
  • Subject: [mg128164] Re: while loop through a list
  • From: Bill Rowe <readnews at>
  • Date: Thu, 20 Sep 2012 00:23:46 -0400 (EDT)
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On 9/19/12 at 4:57 AM, tarpanelli at wrote:

>Hello i've this problem to solve:
>let us suppose I've  a function f which returns a random number and
>I start with an intial list of n random number I would like to check
>if each one of the element of this list is below zero and if it is
>applies the function f till when the new random number is above 0.
>This should be repeated for each element of the list such that at
>the end all the list random numbers will be above 0.

There is no need for an explicit loop to do this. For example:

In[1]:= t = RandomReal[{-1, 1}, 5]

Out[1]= {0.0760855,-0.527881,-0.937804,-0.945365,0.866552}

In[2]:= t /. x_?Negative :> RandomReal[]

Out[2]= {0.0760855,0.953119,0.215987,0.342604,0.866552}

But do note, it is far more efficient to generate random values
in the range desired in the first place.

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