QdObject_var QuGetVectorXYZ(QdObject_var dov)
This returns a QdObject_var of the same underlying type as the input
object, but as a cartesian xyz representation. It returns the input
object if it is already in cartesian. It uses Qu_is3Vector() to ensure
input is a vector with well defined representation and frame. Returns
null var pointer (test with is_nil() ) if a cartesian vector cannot
be constructed. It is used to protect cartesian routines
against polar input representations. e.g.
#include "Qdos.h"
#include "QdUtils.h"
QdObject_var vec_xyz = QuGetVectorXYZ((QdObject_var)vec_in);
QdRMatrixSeq_var vecSeq = QdRMatrixSeq_var::narrow(vec_xyz);
if ( vecSeq.is_nil() ) return QPLUG_FAILURE;