I test case is attached to this message.I solve exactly the same matrix more than one time and I get different result.I can solve 10 times and get 8 times same result and 2 times another result. The next time, I get 6 times sames result and 4 times another result.Maybe you will need to run the case more than 1 time because sometime I get 10 time the same result.At each solve, it's a new surprise for me :)Here is a example result of X whit 5 solve (fill matrix, facotrization and solve) :x = 3.954994 +j 36.454584x = 4.039025 +j 36.871752x = 4.386890 +j 36.496321x = 4.386890 +j 36.496321x = 4.386890 +j 36.496321Marc
Element magnitudes of your matrix vary in a huge range. I saw ones as large as 5000000 and as small as 1e-7. Typically this is not a good sign for numerical stability.
EDIT: Well, it is worse than that. The matrix is singular. The last row is all zeros. Changing the bottom right element to 1 produces a matrix with a 2-condition number of 1.8e27.
Indeed, if the matrix is singular (or highly ill-conditioned) than the solving process is highly unstable and, generally speaking, the result of computations is unpredictable.