[ODE] about odemath

[=?gb2312?B?zfKy/b2t?=]

i want to ask a silly question,in odemath.h, there is a paragraph code as following:

#define dMULTIPLYOP0_331(A,op,B,C) \
  (A)[0] op dDOT((B),(C)); \
  (A)[1] op dDOT((B+4),(C)); \
  (A)[2] op dDOT((B+8),(C));

for (A)[0],i can understand,but for (A)[1] and A[2],i dont understand:
   a0=b0c0+b1c1+b2c2,
for a1,is it right?
   a1=b4c0+b5c1+b6c2

but for A[2],what can it get?