# Highly Nonlinear Approximations for Sparse Signal Representation

##

The need of nonlinear approaches

Even when the subspaces and
are `theoretically'
complementary, in practice, due to the calculations being
performed in finite precision arithmetics, the inaccuracy in the
computation of the corresponding projector may cause the failure to
correctly separate signals in and
. The next
example illustrates the situation.
**Subsections**