title: NLS not working with R
body: <p>I cannot get the nls function to work with r. What am I doing wrong? Here is my code</p>
  
  <pre><code>data = read.table("http://math.univ-lyon1.fr/~gciuperca/lactt.txt", header = FALSE);
  
  plot(data$V1, data$V2)
  
  model &lt;- nls(V2 ~ (a*(V1 + 1)^b)*exp(-c*V1), start = c(a = 0, b = 2, c = 0), data=data)
  </code></pre>
  
  <p>Here is the error I get (It's in French sorry)</p>
  
  <pre><code>Erreur dans nlsModel(formula, mf, start, wts) : 
     matrice de gradient singulière pour les estimations initiales des paramètres
  </code></pre>