'Construct the piecewise polynomial without making checks.
Takes the same parameters as the constructor. Input arguments
`c` and `x` must be arrays of the correct shape and type.  The
`c` array can only be of dtypes float and complex, and `x`
array must have dtype float.'

@classmethod
def construct_fast(cls, c, x, extrapolate=None, axis=0):

    self = object.__new__(cls)
    self.c = c
    self.x = x
    self.axis = axis
    if (extrapolate is None):
        extrapolate = True
    self.extrapolate = extrapolate
    return self
