Picard Iteration for the Characteristic Initial Value Problem in Einstein Equations
arXiv:2609.08421
Abstract
We present an iteration algorithm for vacuum and Einstein scalar-field equations in double-null gauge, which transform the non-linear PDE into systems of ODE. The numerical realization combines characteristic constraint solves, LGL spectral elements, pole-free spherical operators, Galerkin projection, and independent first-order residual and consistency checks.
28 pages, 3 figures, 8 tables