On a classical problem with a complex-valued coefficient and the spectral parameter in a boundary condition
The author studies the completeness, minimality and basis property of the system of root functions of the spectral problem \[ u''(x) + \lambda u(x) = 0,\quad x \in (0,1) \tag{1} \] \[ u(0) = 0,\;u'(1) = d\lambda u(1), \tag{2} \] where \(d\) is an arbitrary nonzero complex number.
scientific article; zbMATH DE number 6136687