Exercise 2.2.29

The average pivots for rand(3) without row exchanges were $\frac{1}{2},5,10$ in one experiment but pivots 2 and 3 can be arbitrarily large. Their averages are actually infinite ! With row exchanges in MATLAB’s lu code, the averages $.75$ and $.50$ and $.365$ are much more stable (and should be predictable, also for randn with normal instead of uniform probability distribution for the numbers in $A$ ).