The circles in Fig. 2b show equal EDs from the center point of the cloud which is also the center point of the PC space . Fig. 2c shows that equal MDs are represented by ellipses in the PC space. Point 6 is again more than two distance units away from the center point, while point 10 is only within one distance unit. The results are the same as for the MD in the original space( Fig. 1b) . As will be shown in the numerical example and in the next paragraph, this is only true when one uses all PCs for the calculation of the MD.