A short note on the appearance of the simplest antilinear ODE in several physical contexts

In this short note, we review several one-dimensional problems such as those involving linear Schroedinger equation, variable-coefficient Helmholtz equation, Zakharov-Shabat system and Kubelka-Munk equations. We show that they all can be reduced to solving one simple antilinear ordinary differential equation $u^{\mathrm{\prime }}\left(x\right)=f\left(x\right)\overline{u\left(x\right)}$ or its nonhomogeneous version $u^{\mathrm{\prime }}\left(x\right)=f\left(x\right)\overline{u\left(x\right)}+g\left(x\right)$, $x\in (0,x_0)\subset \mathbb{R}$. We point out some of the advantages of the proposed reformulation and call for further investigation of the obtained ODE.