pub fn integrate_polynomial(
f: impl FnMut(Scalar) -> GeopResult<Vec<Scalar>>,
breaks: &[Scalar],
components: usize,
degree: usize,
) -> GeopResult<Integral>Expand description
The integral of the components-valued f from breaks[0] to the last
of breaks, where f is a polynomial of degree at most degree between
every two consecutive breaks — a spline, say, split at its knots.
The Gauss–Legendre rule of degree / 2 + 1 points is exact for such an
f, so the result is the rule’s value, enclosed in interval arithmetic,
and nothing else: no truncation error, always converged. Whether f is
such a polynomial is the caller’s claim to make, from what f is; a
degree above MAX_POLYNOMIAL_DEGREE is an error.