Starting new matrix.
mna2  --  Modified node admittance matrix with floating voltage source.
4
1 1  2.0
2 2  1.0
1 3  1.0
1 4  1.0
2 3 -1.0
3 1  1.0
3 2 -1.0
4 1  1.0
0 0  0.0
Beginning source vector.
0.0
0.0
1.0
-1.0