title: Plotting graph using scipy.optimize.curve_fit
body: <p>I am having trouble in understanding the <code>optimize.curve_fit</code> function. My fitting function is a power law. But I don't know exactly what should be the second value in the plot command? First we have to call function <code>ff(L,v)</code> it will return us fitting line but we are not calling this function. How this command is working I want to know that.  </p>
  
  <pre><code>x=Ls
  y=Tc
  #fitting function
  def ff(L,v):
      return L**(-1/v)
  pfit,perr=optimize.curve_fit(ff,x,y)
  plt.plot(x,...)
  </code></pre>