title: how to obtain a curve in scilab
body: <p>I made the following algorithm: </p>
  
  <pre><code>c=3e8;//m/s 
  h=6.6e-34;//J*s 
  lambda=200e-9;//m 
  E=h*c/lambda;//J 
  k0=(2*E)/(h*c);//m^-1 
  l=10; 
  n=1.33; 
  rd=20*10^-6; 
  r=1*10^-9:200:10*rd;//m 
  for i=1:length(r) 
  if r(i)&lt;=rd then 
      Ep(i)=(E*(n^2-1))+(E*l*(l+1)/(k0^2*r(i).^2));//J 
  elseif r&gt;rd then 
      Ep(i)=(E*(n^2-1))+(E*l*(l+1)/(k0^2*r(i).^2)); 
  end 
  end 
  clf 
  plot2d(r,Ep,style=1); 
  </code></pre>
  
  <p>I must obtain a curve and for the moment my program calculates only a value.</p>