title: how to generate random numbers (probabilities) from exponential distribution that sum up to 1
body: <p>Consider I want <code>x</code> random numbers that sum up to one and that distribution is exponential. When I use </p>
  
  <pre><code>x&lt;-c(10,100,1000)
  
  a&lt;-rexp(x[3],rate=1)
  
  a&lt;-a/sum(a)
  </code></pre>
  
  <p>This will change the distribution, right? </p>
  
  <p>So does anybody know a way so that the probabilities are still exponential distributed? I know that they will then not be completely independent anymore.</p>
  
  <p>Thanks a lot!</p>