CPP water-wave capillary-gravity-wave python 人生 Leetcode bessel-functions Hankel-transform hexo-stellar levi-civita exterior-algebra 诗词 continuity-equation euler-equations hankel-transform ray-theory azimuthal-Fourier Discrete-Fourier-transform mathjax latex tensor-calculus dyadic-product vector-calculus special-functions gamma-and-zeta gaussian-integrals fourier-analysis bessel-and-hankel hodge-star metric-tensor 春物 cpp-debug python-lambda PINN academic-eng eulerian-lagrangian-descriptions hydraulic-jump eulerian-and-lagrangian bi-laplacian axisymmetric-PDE stationary-phase dispersion-relation water-waves contour-integrals envelope-geometry wave-action froude-number fourier-transform residue-theorem complex-analysis wave-patterns Dirichlet–Neumann-operator Fourier multipliers Axisymmetry Angular-Fourier-series Bessel-functions Polar-Fourier-transform Heaviside-function azimuthal-fourier mode-diagonalization Linear-recurrence Chebyshev-type-expansions Bessel-operator Sturm-Liouville self-adjointness ladder-operators functional-analysis