I don't actually need centroids marked on dwg as points, I just need their locations so I can place labels there. Here is another image. It is an equilateral triangle where side length=1. 
pt 1 X= 0.5000 Y= 0.2887 Z= 0.0000
pt 2 X= 0.5000 Y= 0.4357 Z= 0.0000
pt 3 X= 0.5000 Y= 0.4330 Z= 0.0000
Pt 1 is my centroid location, that i calculated based on Gille's example.
Pt 2 is center grip point of mpolygon.
Pt 3 is Map centroid created through Topology-Create centroids function.
As it can be seen, all three are different. I'm wondering what the center grip point of mpolygon represents, and how centroid point are calculated in Map.
Definition of centroid:
The centroid of a triangle is the intersection of the three medians of the triangle (each median connecting a vertex with the midpoint of the opposite side).
Centroid that Map gives does not fit in this definition.