Power system state simulation matrices Yunzhi Cheng, UT Arlington.
In MATLAB, the solution to x=A\b is desired, but this can be slow in
MATLAB 7.3 because of the speed of sparse QR as compared to sparse
Cholesky. Using x=(A'*A)\(A'*b) is faster, but of course yields
slightly less accurate (but still acceptable) results. Note that an
initial guess to the solution is provided, for use by an iterative
method. However, sparse Cholesky with an AMD ordering is very fast
for this matrix and thus iterative methods are unlikely to be
competitive.