Construct a new piecewise polynomial representing the antiderivative.
Antiderivativative is also the indefinite integral of the function, and derivative is its inverse operation.
n : int, optional
Order of antiderivative to evaluate. (Default: 1) If negative, the derivative is returned.
pp : PPoly
Piecewise polynomial of order k2 = k + n representing the antiderivative of this polynomial.
The antiderivative returned by this function is continuous and continuously differentiable to order n-1, up to floating point rounding error.