Asymptotic consistency of the WSINDy algorithm in the limit of continuum
data
- URL: http://arxiv.org/abs/2211.16000v1
- Date: Tue, 29 Nov 2022 07:49:34 GMT
- Title: Asymptotic consistency of the WSINDy algorithm in the limit of continuum
data
- Authors: Daniel A. Messenger and David M. Bortz
- Abstract summary: We study the consistency of the weak-form sparse identification of nonlinear dynamics algorithm (WSINDy)
We provide a mathematically rigorous explanation for the observed robustness to noise of weak-form equation learning.
- Score: 0.0
- License: http://creativecommons.org/licenses/by/4.0/
- Abstract: In this work we study the asymptotic consistency of the weak-form sparse
identification of nonlinear dynamics algorithm (WSINDy) in the identification
of differential equations from noisy samples of solutions. We prove that the
WSINDy estimator is unconditionally asymptotically consistent for a wide class
of models which includes the Navier-Stokes equations and the
Kuramoto-Sivashinsky equation. We thus provide a mathematically rigorous
explanation for the observed robustness to noise of weak-form equation
learning. Conversely, we also show that in general the WSINDy estimator is only
conditionally asymptotically consistent, yielding discovery of spurious terms
with probability one if the noise level is above some critical threshold and
the nonlinearities exhibit sufficiently fast growth. We derive explicit bounds
on the critical noise threshold in the case of Gaussian white noise and provide
an explicit characterization of these spurious terms in the case of
trigonometric and/or polynomial model nonlinearities. However, a silver lining
to this negative result is that if the data is suitably denoised (a simple
moving average filter is sufficient), then we recover unconditional asymptotic
consistency on the class of models with locally-Lipschitz nonlinearities.
Altogether, our results reveal several important aspects of weak-form equation
learning which may be used to improve future algorithms. We demonstrate our
results numerically using the Lorenz system, the cubic oscillator, a viscous
Burgers growth model, and a Kuramoto-Sivashinsky-type higher-order PDE.
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