The paper reports on a graphical user interface developed in MATLAB to aid the visualization of the plane wave impinging from a lossless half-space onto a multilayer structure. Individual layers are assumed to be homogeneous and isotropic with electric permittivity (∊) and magnetic permeability (μ) taking arbitrary complex values. Double-positive, single-negative and double-negative media (real parts of ∊ and μ) as well as lossless, dissipative and amplifying media (imaginary parts of ∊ and μ) are allowed. 2D field distribution, transmission and reflection coefficients, and the wave vectors' z-component locations in the complex plane are presented to the user.