>>> from astropy.modeling import *
>>> x = np.arange(1, 10, .1)
>>> p1 = models.Poly1DModel(2, param_dim=2)
>>> p1.parameters = [1, 1, 2, 2, 3, 3]
>>> p1.param_sets
array([[ 1., 1.],
[ 2., 2.],
[ 3., 3.]])
>>> y = p1(x)
>>> p1.c1.fixed = True
>>> pfit = fitting.LinearLSQFitter(p1)
fitting.rstcontains the following example.The last line raises the exception:
InputParameterError: Parameter of <type 'list'> could not be converted to float