  The aim of this work is to propose an alternative method for determining the
condition of existence of "canard solutions" for three and four-dimensional
singularly perturbed systems with only one fast variable in the folded saddle
case. This method enables to state a unique generic condition for the existence
of "canard solutions" for such three and four-dimensional singularly perturbed
systems which is based on the stability of folded singularities of the
normalized slow dynamics deduced from a well-known property of linear algebra.
This unique generic condition is perfectly identical to that provided in
previous works. Application of this method to the famous three and
four-dimensional memristor canonical Chua's circuits for which the classical
piecewise-linear characteristic curve has been replaced by a smooth cubic
nonlinear function according to the least squares method enables to show the
existence of "canard solutions" in such Memristor Based Chaotic Circuits.
