Neumann (top) and Dirichlet (bottom) Boundary Conditions
a1 + c1	b1	0	0	0	0	0	0	0	0	0		u1		f1
c2	a2	b2	0	0	0	0	0	0	0	0		u2		f2
0	c3	a3	b3	0	0	0	0	0	0	0		u3		f3
0	0	c4	a4	b4	0	0	0	0	0	0		u4		f4
0	0	0	c5	a5	b5	0	0	0	0	0		u5		f5
0	0	0	0	c6	a6	b6	0	0	0	0	´	u6	=	f6
0	0	0	0	0	c7	a7	b7	0	0	0		u7		f7
0	0	0	0	0	0	c8	a8	b8	0	0		u8		f8
0	0	0	0	0	0	0	c9	a9	b9	0		u9		f9
0	0	0	0	0	0	0	0	c10	a10	b10		u10		f10
0	0	0	0	0	0	0	0	0	c11	a11		u11		f11 - b11u12

Periodic Boundary Conditions
a1	b1	0	0	0	0	0	0	0	0	c1		u1		f1
c2	a2	b2	0	0	0	0	0	0	0	0		u2		f2
0	c3	a3	b3	0	0	0	0	0	0	0		u3		f3
0	0	c4	a4	b4	0	0	0	0	0	0		u4		f4
0	0	0	c5	a5	b5	0	0	0	0	0		u5		f5
0	0	0	0	c6	a6	b6	0	0	0	0	´	u6	=	f6
0	0	0	0	0	c7	a7	b7	0	0	0		u7		f7
0	0	0	0	0	0	c8	a8	b8	0	0		u8		f8
0	0	0	0	0	0	0	c9	a9	b9	0		u9		f9
0	0	0	0	0	0	0	0	c10	a10	b10		u10		f10
b11	0	0	0	0	0	0	0	0	c11	a11		u11		f11