title: Automatic curve fitting in R
body: <p>Is there any package that automatically fits a curve using many simple models?<br>
  By simple models I mean:  </p>
  
  <ul>
  <li>ax+b  </li>
  <li>ax^2+bx+c</li>
  <li>a*log(x) + b</li>
  <li>a*x^n+b</li>
  <li>ax/(1+bx)  </li>
  <li>ax^n/(1+bx^n)</li>
  <li>...  </li>
  </ul>
  
  <p>The best would be to have a function that takes two vector parameters X and Y and returns a list of fitted simple models with their SSE.</p>