Neural Spectral Methods: Self-supervised learning in the spectral domain
Yiheng Du, Nithin Chalapathi, Aditi Krishnapriyan

TL;DR
Neural Spectral Methods introduce a spectral loss-based approach for solving parametric PDEs that outperforms existing machine learning and numerical methods in speed and accuracy, with constant inference cost.
Contribution
The paper proposes a novel spectral loss strategy for neural spectral methods, improving training efficiency and inference speed for PDE solutions.
Findings
Outperforms previous ML approaches by 10-100x in speed and accuracy
Maintains constant inference cost regardless of domain resolution
Achieves 10x faster performance than numerical solvers at same accuracy
Abstract
We present Neural Spectral Methods, a technique to solve parametric Partial Differential Equations (PDEs), grounded in classical spectral methods. Our method uses orthogonal bases to learn PDE solutions as mappings between spectral coefficients. In contrast to current machine learning approaches which enforce PDE constraints by minimizing the numerical quadrature of the residuals in the spatiotemporal domain, we leverage Parseval's identity and introduce a new training strategy through a \textit{spectral loss}. Our spectral loss enables more efficient differentiation through the neural network, and substantially reduces training complexity. At inference time, the computational cost of our method remains constant, regardless of the spatiotemporal resolution of the domain. Our experimental results demonstrate that our method significantly outperforms previous machine learning approaches…
Peer Reviews
Decision·ICLR 2024 poster
The paper is well written and the method section is easy to follow. The spectral loss seems like a promising direction for solving PDEs with Neural Networks. Experimentally, the method outperforms all considered baselines in terms of L2 relative error. Reaction-diffusion and Navier-stokes experiments were done for different values of diffusion and viscosity coefficients, which highlights the robustness of the method. Figures 2 and 3 show that NSM converges faster during training and is also ins
The motivation of the paper is not transparent to me. The authors propose in this paper two novelties for PDE-based neural networks : a spectral loss and a general design for spectral-based neural operators. While I understand that the first is supposed to simplify the training of PINNs, the second one seems to be a new architecture for solving operator learning tasks like FNO or SNO. Therefore, their method is not a PINN-like solver with a new loss, but rather a deep surrogate model that can ap
**Originality:** The paper has several novelties, including a new design of neural operator with fixed bases. A novel residual loss by Parseval's identity. **Quality:** The paper has carefully benchmarked the proposed method in training cost, inference cost and accuracy. It exhibits advantages over several baseline methods. **Clarity:** The paper is well organized and clearly presented. **Significance:** The proposed method can in inspiring to the community in both
More comparison can be done, for example, Transform Once >Poli, Michael, et al. "Transform once: Efficient operator learning in frequency domain." Advances in Neural Information Processing Systems 35 (2022): 7947-7959. which can be combined with PINN loss or the loss proposed here.
Like discussed in the summary, the strength of the paper is the elegance integrating NNs with existing spectral methods. In particular, spectral basis are used to represent the functions and NNs are only used to map from spectral coefficients to spectral coefficients (with neural operator architecture). In addition, by leveraging the Parseval's Identity, the proposed method is able to train without using the expensive PDE residual norm (PINN loss). The authors mathematically proved the equivalen
The paper briefly mentions some limitations of existing ML methods for solving PDEs, but it could benefit from a more extensive discussion of the potential drawbacks and challenges specific to NSM. Basis are predefined manually. It's unclear how to choose these basis functions.
Code & Models
Videos
Taxonomy
TopicsModel Reduction and Neural Networks
MethodsSPEED: Separable Pyramidal Pooling EncodEr-Decoder for Real-Time Monocular Depth Estimation on Low-Resource Settings
