Inverse solutions are key problems in many natural sciences. They form the basis of
our understanding of the world surrounding us. Whenever we try to learn something
about physical laws, the internal structure of the earth or the nature of the Universe,
we collect data and try to extract the required information from these data. This is the
actual solution of the inverse problem. In fact the observed data are predetermined
by physical laws, and by the structure of the earth or Universe. The method of
predicting observed data for given sources within given media is usually referred
to as the forward problem solution. The method of reconstructing the sources of
some physical, geophysical, or other phenomenon, as well as the parameters of the
corresponding media, from the observed data is referred to as the inverse problem
solution.