title: Matlab Plotting x=a?
body: <p>How can I draw i.e. x = 5 line in plot at Matlab?</p>
  
  <p>I plot like that:</p>
  
  <pre><code>x = (-10:.1:10); 
  f= 10;
  plot(x, f, 'r');
  </code></pre>
  
  <p>of course it doesn't work. For every variable of x, y is equal to 0 except for x=10. When x = 10 y equals to everything. How to plot this?</p>