Replace an unconstrained Neural ODE vector field with nonnegative production and destruction networks and discretize the resulting dynamics by an NSFD rational update. The update remains nonnegative for every step size, allowing stable coarse-step training and inference without clipping, projection, or tiny adaptive solver steps.
Replace explicit RK integration in a stiff neural ODE or continuous-depth residual network with the paper's stiffly accurate SDIRK4 discretization. Instead of performing a dense Newton solve for each implicit stage, solve the diagonal stage equation using a Chebyshev-accelerated residual iteration whose polynomial damps the negative, high-magnitude Jacobian modes responsible for stiffness.