Graded L1-2-3 time stepping and adaptive tension splines for two-dimensional time-fractional reaction–diffusion equations
This paper proposes a high-order numerical method for two-dimensional time-fractional reaction–diffusion equations by introducing an adaptive tension spline spatial operator that selects optimal parameters based on local solution modes and a stable L1-2-3 time-stepping scheme on graded meshes, thereby achieving a temporal convergence order of approximately while correcting misconceptions regarding fourth-order accuracy in existing non-polynomial spline literature.