title: How to fill matrix with random numbers in R?
body: <pre><code>expand.grid(i=rexp(5,rate=0.1))
  </code></pre>
  
  <p>It creates just one col but is there some way to multiply this easily to 5 cols? I mean the matlab-way-of-doing-things like <code>rand('exp', 0.1, 10,20)</code> (creating a matrix with exponentially-distributed-random-numbers with mean 0.1 of size 10x20), how?</p>