Fig. 1.
Left: left hippocampus surface, heat diffusion with σ = 1.5 using the Chebyshev, Hermite and Laguerre approximation methods with degree m = 100. Right: MSE between the original surface and the polynomial approximation methods for different expansion degree m. The Hermite approximation method has the slowest convergence, while the Chebyshev method converges slightly faster than the Laguerre method. But the all the methods converge quickly with degree m = 100.