The Fourier-family assembly and the 1D single-mode assembly agree on the lowest eigenvalue of the analytic screw-pinch case only to about 3.5e-8 relative, and the residual moves with the angular grid resolution although all integrands should be band-limited. Both derive from the same kernel by linearity, so a subtle quadrature or condensation-order difference remains to be isolated. The cross-check tolerance in test_family_assembly.f90 is set to 1e-6 until this is explained.
The Fourier-family assembly and the 1D single-mode assembly agree on the lowest eigenvalue of the analytic screw-pinch case only to about 3.5e-8 relative, and the residual moves with the angular grid resolution although all integrands should be band-limited. Both derive from the same kernel by linearity, so a subtle quadrature or condensation-order difference remains to be isolated. The cross-check tolerance in test_family_assembly.f90 is set to 1e-6 until this is explained.