title: Fitting differential equations: how to fit a set of data to a differential equation in R
body: <p>With a data set:</p>
  
  <pre><code>conc &lt;- data.frame(time = c(0.16, 0.5, 1.0, 1.5, 2.0, 2.5, 3), concentration = c(170, 122, 74, 45, 28, 17, 10))
  </code></pre>
  
  <p>and I would like to fit this data to the differential equation below:</p>
  
  <pre><code>dC/dt= -kC
  </code></pre>
  
  <p>where C would be the concentration, and time t in the data set. This would also give a result of k. Could anybody give me a clue how to do this in R? Thanks.</p>