n 
(36) 
13 
dz = dz 0 + z—\-xdx (32) 
s 
In this type of adjustment, it is always suitable to use the center of gravity 
of the given points as coordinate origin. 
The coordinates of the center of gravity are for n points 
[x] 
* c = — 
n 
[z] 
Z c = — 
n 
The coordinates of an arbitrary point i in this system are 
[x] 
n 
Z. = Zi 
n 
The error equations can now be written as residual correction equations as 
follows 
ds 
v x = — dx 0 — X—t-Zdx — dx (33) 
s 
v z =- dz 0 -Z-- Xdx - dz (34) 
s 
For n points the normal equations become 
ndx 0 + [dx] =0 
ndz 0 + [dz]=0 
ds (35) 
([XX] + [ZZ])- + [Xdx] + \Zdz~] = 0 
s 
([XX] + \ZZ])dx - [Zdx] + [Xdz] = 0 
The solution of these equations is