code: public static void extractColumn(DMatrixRMaj P, int col, GeoTuple3D_F64 a) {
  		a.x = P.unsafe_get(0,col);
  		a.y = P.unsafe_get(1,col);
  		a.z = P.unsafe_get(2,col);
  	}
docs: Extracts a column from the camera matrix and puts it into the geometric 3-tuple.