FullGenLinSOE is class which is used to store a full general
system. The A matrix is stored in a 1d double array with n*n
elements, where n is the size of the system. A_{i,j} is stored at
location (i + j*(n), where i and j range from 0 to n-1,
i.e. C notation. For example when n=3:
\left[
\begin{array}{ccc}
a_{0,0} & a_{0,1} & a_{0,2}