+ /** Bareiss fraction-free elimination. This is a modification of
+ * Gauss elimination where the division by the pivot element is
+ * <EM>delayed</EM> until it can be carried out without computing
+ * GCDs. If \f$m_{i,j}^{(0)}\f$ are the entries of the original
+ * matrix, then the matrix is transformed into triangular form by
+ * applying the rules
+ * \f[
+ * m_{i,j}^{(k+1)} = (m_{i,j}^{(k)} m_{k,k}^{(k)} - m_{i,k}^{(k)} m_{k,j}^{(k)}) / m_{k-1,k-1}^{(k-1)}
+ * \f]
+ * (We have set \f$m_{-1,-1}^{(-1)}=1\f$ in order to avoid a case
+ * distinction in above formula.) It can be shown that nothing more
+ * than polynomial long division is needed for carrying out the
+ * division. This is generally the fastest algorithm for solving
+ * linear systems. In contrast to division-free elimination it only
+ * has a linear expression swell. For two-dimensional systems, the
+ * two algorithms are equivalent, however. */