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DeepONet + 1D Poisson + Laplace

Notebook: DeepONet_Poisson1D_Laplace_Tutorial.ipynb

This tutorial builds a 1D scientific machine learning example around the boundary value problem

\[ -u''(x) = f(x), \qquad x \in [0, 1], \qquad u(0)=u(1)=0. \]

It uses a DeepONet1D surrogate to learn the field-to-field map from a forcing field \(f(x)\) to the equilibrium response field \(u(x)\), then adds a last-layer Laplace approximation to quantify predictive uncertainty.

What the notebook covers:

  • physical meaning of the Poisson problem in diffusion / elasticity / electrostatics language,
  • dataset generation from random smooth forcing fields,
  • DeepONet branch/trunk structure for 1D operator learning,
  • MAP training diagnostics,
  • uncertainty bands over the 1D spatial coordinate,
  • in-domain vs OOD comparisons for uncertainty calibration.

Why this notebook is useful:

  • both the input and the output are 1D fields, so the neural-operator map is easy to interpret,
  • uncertainty is visible as a standard mean-curve plus confidence-band plot,
  • the Poisson solver is stable and inexpensive, which keeps the tutorial focused on operator learning rather than PDE debugging.