D. Matrix Method

 1. General

The Matrix method is a third way to perform an LS adjustment, using matrix algebra incorporating principles in the XIV. Simultaneous Equations topic.
The baisc premise for all three methods is the same: minimizing the sum of the squares of the residuals. The methods differ in how that is achieved. The Brute Force method begins with averages since those statistically meet the minimization criterion. The Direct Minimization method starts with observation equations written in terms of residuals, which are then minimized by derivation, and unknowns solved simultaneously.

The Matrix method is an extension of Direct Minimization using observation equations to build matrices, manipulate them, and solve simultaneous equations.