title: How to plot arrow with data coordinates in Matlab?
body: <p>I know there is a function named annotation can plot arrows or double arrows. But annotation can only plot in normalized unit. For example:</p>
  
  <pre><code>annotation('arrows',[x1 x2],[y1 y2])
  </code></pre>
  
  <p>Here, [x1, x2] should be a ratio number less than one.</p>
  
  <p>So, my question is how can I plot arrows with a true value rather than a normalized value?</p>
  
  <p>I wonder if there is any other function can approach this or is there any function I can get the axis value of the figure so that I can adjust the true value into a normalized value.</p>