title: "func() missing 3 required positional arguments: 'b', 'c', and 'd'"
body: <p>I am trying to fit a Gaussian with on the following dataset (could not paste it all but hopefully that is enough rows)</p>
  
  <pre><code>2.738237424 0.1956847
  2.742886384 0.1956847
  2.747535344 0.1956847
  2.752184304 0.1956847
  2.756833264 0.1776788
  2.761482224 0.1956847
  2.766131184 0.1956847
  2.770780144 0.1776788
  2.775429104 0.1776788
  2.780078064 0.1956847
  2.784727024 0.1956847
  2.789375984 0.1956847
  2.794024944 0.1776788
  2.798673904 0.1776788
  2.803322862 0.1956847
  </code></pre>
  
  <p>Here is my code:
      x = data[590:880,0]
      y = data[590:880,1]</p>
  
  <pre><code>error = np.repeat(0.001, (880 - 590))
  
  # Model object
  def func(x, a, b, c, d):
      return a*np.exp(-(x-b)**2/c**2) + d
  
  quad_model = odr.Model(func)
  
   # Create a RealData object
  dataset = odr.RealData(x, y, sx=error)
  
  # Set up ODR with the model and data.
  odr = odr.ODR(dataset, quad_model, beta0=[-0.6, 3.7, -0.4, 0.2])
  </code></pre>
  
  <p>I get the message "func() missing 3 required positional arguments: 'b', 'c', and 'd'"
  Do you know what is going on?</p>
  
  <p>Thank you!</p>