CASTOR: normal-mode analysis of resistive MHD plasmas. The CASTOR (complex Alfvén spectrum of toroidal plasmas) code computes the entire spectrum of normal modes in resistive MHD for general tokamak configurations. The applied Galerkin method, in conjunction with a Fourier finite element discretisation, leads to a large scale eigenvalue problem 𝐀x ̲=λ𝐁x ̲, where 𝐀 is a nonself-adjoint matrix. © Academic Press.