Proposed new feature or change:

The current default values for both domain and window parameters are both np.array([-1, 1]). On the other hand, if we call __init__ with 3 parameters, then domain and window always get cast to double. This leads to the following behaviour:

>>> p1 = P(np.array([1,2,3]))
>>> p1
Polynomial([1., 2., 3.], domain=[-1,  1], window=[-1,  1], symbol='x')
>>> p2 = P(np.array([1,2,3]), np.array([-1, 1]), np.array([-1,1]))
>>> p2
Polynomial([1., 2., 3.], domain=[-1.,  1.], window=[-1.,  1.], symbol='x')
>>> p1.domain.dtype
dtype('int64')
>>> p2.domain.dtype
dtype('float64')

Changing the default values of the parameters domain and window to np.array([-1., 1.]) will increase consistency between constructors Polynomial(coef) and Polynomial(coef, domain, window).