·行阶梯形 1 0. 0C1r 1.01n 0 1 0C2r+1 .C2n .: : I= 0 0 1Crr+l .Crn : : 00 .0Cr+1 .Cmn• 行阶梯形                   = + + + + mn rn n n mr rr r r c c c c c c c I                      2 1 1 1 2 1 1 1 0 0 0 0 0 0 1 0 1 0 1 0 0