  The superposition principle is usually incorrectly applied in interference
experiments. This has recently been investigated through numerics based on
Finite Difference Time Domain (FDTD) methods as well as the Feynman path
integral formalism. In the current work, we have derived an analytic formula
for the Sorkin parameter which can be used to determine the deviation from the
application of the principle. We have found excellent agreement between the
analytic distribution and those that have been earlier estimated by numerical
integration as well as resource intensive FDTD simulations. The analytic handle
would be useful for comparing theory with future experiments. It is applicable
both to physics based on classical wave equations as well as the
non-relativistic Schrodinger equation.
