Why is a Matrix Not Invertible?
For our WNBA Massey Matrix model, some adjustments need to be made for a solution to our rating problem to exist and be unique.
To see this, notice that the following code produces an error:
> print(M)
1 33 -4 -2 -3 -3 -3 -3 -3 -3 -3 -3 -3
2 -4 33 -3 -3 -3 -3 -2 -3 -3 -3 -3 -3
3 -2 -3 34 -3 -3 -3 -3 -4 -4 -3 -3 -3
4 -3 -3 -3 34 -3 -4 -3 -3 -2 -3 -3 -4
5 -3 -3 -3 -3 33 -3 -3 -3 -3 -3 -2 -4
6 -3 -3 -3 -4 -3 41 -8 -3 -6 -3 -2 -3
7 -3 -2 -3 -3 -3 -8 41 -3 -4 -3 -3 -6
8 -3 -3 -4 -3 -3 -3 -3 34 -3 -2 -3 -4
9 -3 -3 -4 -2 -3 -6 -4 -3 38 -3 -4 -3
10 -3 -3 -3 -3 -3 -3 -3 -2 -3 32 -4 -2
11 -3 -3 -3 -3 -2 -2 -3 -3 -4 -4 33 -3
12 -3 -3 -3 -4 -4 -3 -6 -4 -3 -2 -3 38
> solve(M)
Error in solve.default(M) :
system is computationally singular: reciprocal condition number = 3.06615e-17
Which of the conditions does \(M\) explicitly violate in this case?
This exercise is part of the course
Linear Algebra for Data Science in R
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