publication Journal Article 2026 Quartic Rational Iterations for the Matrix Sign with Applications to Principal Square Roots and Inverse Square Roots. more of publication Fourier and Shape-Parameter Analysis of Compact Multiquadric RBF–HFD Approximations on Nonuniform Stencils. 2026 A Spectral Galerkin Framework for the Fractional Reaction–Subdiffusion Equation Using Legendre Cardinal Functions. 2026 Quartic Rational Iterations for the Matrix Sign with Applications to Principal Square Roots and Inverse Square Roots. 2026