Function polynomial_flow 

pub fn polynomial_flow<V: ValueAlgebra>(
    field: &V,
    vector: &V,
    n: &V,
) -> Result<V, String>

N passes of x ← x + dt·f(x) + O(dt²), f polynomial with rational coefficients. A finite N runs the update itself. An infinite one, N = T/dt + δ on each residue class, ends infinitely close to the solution of x' = f(x) from the start’s standard part at time T, a germ known by its standard part; a scalar solution certified to leave every bound before T leaves an unlimited germ.