title: Algorithm to find the minimum value point of a function
body: <p>I would like to find the lowest value of a function with the least number of trials. The function <code>f(x)</code> must have a point with minimum value. Given input <code>x</code>, I can calculate <code>f(x)</code>, but not the other direction. I don't have the explicit expression of the function, so it is a blackbox.</p>
  
  <p>I would like to find the input <code>x</code> such that minimizes <code>f(x)</code>, with the least number of trials (One trial is when I choose a specific x, and plug it in to get the output). Are there any algorithms to achieve that?</p>
  
  <p>The result doesn't need to be the absolute minimum, since it is derived from a real problem. But it should be less than most of the values.</p>
  
  <p>If the function is constrained to be convex, is there a better way to achieve that?</p>
  
  <p>Thanks!</p>