title: Matlab Spline Interpolation Find X from Y
body: <p>I need to find the value of x when y = 0.</p>
  
  <p>This is my code:</p>
  
  <pre><code>x=[2,3,4,5,6]; 
  y=[10,8,4,1,-2]; 
  xi=linspace(2,6,100); 
  yi=interp1(x,y,xi,'spline'); 
  plot(x,y,'o',xi,yi,'-') 
  xlabel('x')
   ylabel('y') 
  title('Data')
  </code></pre>
  
  <p>I tried using fzero, but I couldn't figure out the proper syntax.</p>
  
  <p>I do not have a function f(x) to use, only the points given.</p>