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POGet a randomized aberrancy around given value
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  1. POGet a randomized aberrancy around given value
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    copied!<p>I would like to add a kind of ripple to an array of known values of type <strong>double</strong>. I point that out because Random.Next / Random.NextDouble() behave different.</p> <p>How do i best achieve this task?</p> <p>Let say i have 20 values in the array, <br> <code>List&lt;double&gt; arr = new List&lt;double&gt;() { 40, 40, 40, 40 ..... };</code><br> 20 values which are averaged on amount 40, with a total of 800, to make it easier.</p> <p>After this method, I would like the <em>overall total</em> still remain 800, but each individual value should ben modified. The values should be positive, because they are <code>total+=i</code> added afterwards.</p> <p>So far this problem are solved using a percentage of the given quantity of values. <br> <code>1.0 / 20 = 0.05, then multiplicate that with the total and the iteration number. Then subtract the result from the remainder. Finally i just return a sort by new Guid()</code>.</p> <p>As you already see, this method was only a little terrific, while there was just about 5-20 values. In my case today, this array need to stand 500-2000 values (0,2-0,05% each value). </p> <p>Instead I would like to have a derivative or such, that make a distortion with +-x% of value 40 as base. Or, perhaps even better, +-x% on whatever single value in the array).</p> <p><strong>[UPDATE]</strong></p> <p>I will add the question with an update based on the replies on this question.</p> <pre><code> Random rnd = new Random(); List&lt;double&gt; ripple = new List&lt;double&gt;(); int qty = bArray.Count(); double diff = last.Value - first.Value; if (qty == 1) { double linearAvg = (diff / qty) / 2; ripple.Add(linearAvg); } else { double[] rndarr = new double[qty]; for (int i = 0; i &lt; qty; i++) rndarr[i] = rnd.NextDouble(); double rndArrSum = rndarr.Sum(); for (int i = 0; i &lt; qty; i++) rndarr[i] /= rndArrSum; for (int i = 0; i &lt; qty; i++) ripple.Add(diff * rndarr[i]); } double valueOverall = first.Value; for (int i = (qty &gt; 1) ? 1 : 0; i &lt; qty; i++) valueOverall += ripple[i]; </code></pre> <p>Allowance has been made for the last generated value not to overlap. In addition, an exception when the list contains only two values​​. The <code>qty=1</code> may look magic, but it refers to how the object bArray looks like in real. I think the whole idea is clear anyway.</p>
 

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