title: Method signature for Jacobian of a least squares function in scipy
body: <p>Can anyone provide an example of providing a Jacobian to a <a href="http://docs.scipy.org/doc/scipy/reference/generated/scipy.optimize.leastsq.html#scipy.optimize.leastsq" rel="nofollow noreferrer">least squares function</a> in <code>scipy</code>?</p>
  
  <p>I can't figure out the method signature they want - they say it should be a function, yet it's very hard to figure out what input parameters in what order this function should accept.</p>