1. In a recent paper Mammana considered the equation
z″ + pz′ + qz = 0,.....(1)
where x is the independent variable and p and q are functions of x, real, finite and continuous in the interval (a, b), and investigated the possibilities of its decomposition into the form
(D + α)(D + β)z = 0,.....(2)
where D ≡ d/dx and α and β are functions of x.