Figure 1From: Fourier-Hankel solution of the Robin problem for the Helmholtz equation in supershaped annular domains Relative boundary error e N as a function of order N of the truncated Fourier-Hankel series expansion representing the solution of the Robin problem for the Helmholtz equation in the supershaped annulus described by the Gielis formula with parameters k x ± = k y ± =4 , d x − = d y − =3/4 , d x + = d y + =5/2 , ν x ± = ν y ± =6 , ν 0 ± =10 . Back to article page