title: How to estimate computation time by the number of loops
body: <p>If I know how many loops an algorithm in R will need to complete the task, how could I estimate the computational time?</p>
  
  <p>Here an example: </p>
  
  <pre><code>length(vector_a); # 30000
  length(vector_b); # 100000
  
  for (i in vector_a) {
     for (j in vector_b) {
  print("This is one loop")
     }
  }
  </code></pre>
  
  <p>Then I should have 30,000 * 100,000 = 3,000,000,000 loops before completing the job. Now if I have a 2.6Ghz computer with 4GB of memory how long should take? How do you do the math?</p>