```Date: Nov 15, 2013 6:53 AM
Author: emammendes@gmail.com
Subject: Re: Help with Manipulate

HelloMany many thanks.I went through the code you sent me to see if I can understand it.   There is one piece that I don't understand.  Here is it> (z = generate[\[Lambda], n]) &Why do I need &?  Thanks again.CheersEdOn Nov 14, 2013, at 8:39 AM, Waclaw Kusnierczyk <waku@idi.ntnu.no> wrote:> Will this solve your problem:>> With[{generate =>   RandomVariate[Quiet@ExponentialDistribution[#1], #2 - 1] &},> Module[{z},>  Manipulate[>   z = generate[\[Lambda], n];>   n/Total[z],>   Button["generate", (z = generate[\[Lambda], n]) &],>   {{\[Lambda], 2}, 1, 100, 1},>   {{n, 10000}, 2, 1000000, 1000}]]]>> Best,> vQ>>> On 11/14/2013 08:11 AM, Eduardo M. A. M. Mendes wrote:>>>> I need to create a simple demonstration based upon an exercise on poisson counting processes.  Here is the code>>>> Manipulate[n/Total[z],Style["Poisson Arrival Times",18,Bold],"",Delimiter,{{z,Flatten[{0,RandomVariate[Quiet@ExponentialDistribution[\[Lambda]],n-1]}]},Button["random",z=Flatten[{0,RandomVariate[Quiet@ExponentialDistribution[\[Lambda]],n-1]}]]&,Appearance->"Labeled"},"",Delimiter,{{\[Lambda],2,"\[Lambda]"},1,100,1,Appearance->"Labeled"},"",Delimiter,{{n,10000,"n"},1,1000000,1000,Appearance->"Labeled"},SaveDefinitions->True]>>>> The idea is to generate a sequence of random numbers, then take the sum of it and keep the last value.   Every time I hit "random"a new sequence is created.>>>> The above code returns the following error msg>>>> RandomVariate::array :  "\"The array dimensions -1 + n given in position 2 \>> of RandomVariate[ExponentialDistribution[=CE=BB], -1 + n] should be a list of \>> non-negative machine-sized integers giving the dimensions for the result. \"">>>> and some weird output.   After hitting "random",  the output is what I expect but the whole Manipulate output is still red indicating that there are problems.>>>> Could you be so kind to point out what I did wrong and how to fix it? I feel that I did not quite get how Manipulate works.
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