title: poisson distribution (dpois) integration R
body: <p>I'm trying to integrate the poisson distribution (dpois) in R but I get an incorrect answer (0 with absolute error 0) and 21 warnings. I don't understand how R is digesting my simple meal and why it pukes out 21 warnings. </p>
  
  <pre><code>    dpoisd1 &lt;- function(x) {dpois(x, 0.0001)}
      dpoisd1(1:20)
      integrate(dpoisd1, lower = 1, upper = 20)
  </code></pre>
  
  <p>it yields 0 with absolute error &lt; 0 and some 21 warnings. I would really appreciate it if someone could show me my mistake(s).</p>