(Optional) Set the (components of) the Nedelec interpolation matrix
.
This function is generally intended to be used only for high-order Nedelec
discretizations (in the lowest order case, 
is constructed internally in
AMS from the discreet gradient matrix and the coordinates of the vertices),
though it can also be used in the lowest-order case or for other types of
discretizations (e.g. ones based on the second family of Nedelec elements).
By definition, is the matrix representation of the linear operator that
interpolates (high-order) vector nodal finite elements into the (high-order)
Nedelec space. The component matrices are defined as 
and similarly for 
and 
. Note that all these
operators depend on the choice of the basis and degrees of freedom in the
high-order spaces.
The column numbering of Pi should be node-based, i.e. the 
/
/
components of the first node (vertex or high-order dof) should be listed
first, followed by the // components of the second node and so on
(see the documentation of HYPRE_BoomerAMGSetDofFunc).
If used, this function should be called before HYPRE_AMSSetup() and there is
no need to provide the vertex coordinates. Furthermore, only one of the sets
and 
needs to be specified (though it is OK
to provide both). If Pix is NULL, then scalar -based AMS cycles,
i.e. those with cycle_type > 10, will be unavailable. Similarly, AMS cycles
based on monolithic (cycle_type < 10) require that Pi is not NULL.
