  A family of triaxial St\"ackel potential-density pairs is introduced. With
the help of a Quadratic Programming method, a linear combination of
potential-density pairs of this family which fits a given projected density
distribution can be built. This deprojection strategy can be used to model the
potentials of triaxial elliptical galaxies with or without dark halos. Besides,
we show that the expressions for the St\"ackel triaxial density and potential
are considerably simplified when expressed in terms of divided differences,
which are convenient numerically. We present an example of triaxial
deprojection for the galaxy NGC~5128 whose photometry follows the de
Vaucouleurs law.
