(1)作A的LU分解 b1=3 b 23677 33 615 l3=b3-l3c2=3-= 738 l1=b-l1C2=3 15 15151 1 u = b 1 2 2 u a l = 2 2 2 1 u = b - l c = 3 3 2 = 3 7 3 2 = 3 - = 2 3 3 u a l = 7 6 = 3 3 3 2 u = b - l c 7 15 7 6 = 3 - = 3 4 4 u a l = 15 7 = 4 4 4 3 u = b - l c 15 38 15 7 = 3 - = (1) 作A的LU分解