  The field of real numbers being extended as a larger commutative field, we
investigate the possibility of defining a scalar product for the distributions
of finite discrete support. Then we focus on the most simple possible extension
(which is an ordered field), we provide explicit formulas for this scalar
product, and we exhibit a structure of positive definite inner-product space.
In a one-dimensional application to the Schroedinger equation, the
distributions supported by the origin are embedded into a bra-ket vector space,
where the "singular" potential describing point interaction is defined in a
natural way. A contact with the hyperreal numbers that arise in nonstandard
analysis is possible but not essential, our extensions of $\bf R$ and $\bf C$
being obtained by a quite elementary method.
