  In a central potential the usual resolution of the Schr\"odinger equation in
spherical coordinates consists in determining the solutions R(r) or u(r) of the
radial equations considered as the radial parts of the Schr\"odinger equation.
However, the solutions must be supplemented with the boundary condition u(0) =
0 in order to rule out singular solutions. There is still no consensus to
justify this condition, with good reason. It is based on a misunderstanding
that comes from the fact that the radial equation in terms of R(r) is derived
from the Schr\"odinger equation, and the radial equation in terms of u(r) from
the former, by taking the Laplacians in the sense of the functions. By taking
these Laplacians in the sense of the distributions, as it is required, we show
that the radial equations are derived from the Schrodinger equation when their
solutions are regular, but not when they are singular, so that the equations
need not be supplemented with any supplementary condition such as u(0) = 0.
