矩阵和矩阵相乘 a11a12 C C12 a21 a22 b2 b22 … C=AB= C21 C22 C2k n…amb b之 Cn2 Cnk nxm m×k nxk
矩阵和矩阵相乘 = = = n n n k k k m m m k k k n n n m m m c c c c c c c c c b b b b b b b b b a a a a a a a a C AB 1 2 2 1 2 2 2 1 1 1 2 1 1 2 2 1 2 2 2 1 1 1 2 1 1 2 2 1 2 2 2 1 1 1 2 1 nm mk nk
Cu= (i=1,2,,n,jF1,2,,k) (3.17) av2 ym … C12 021 0422 C2m b21 b22 … bak C21 C22 C2k n2 Cn2
= = m p ij aip ppj c 1 (i = 1, 2, …, n, j= 1,2, …, k) (3.17) = n n n k k k m m m k k k n n n m m m c c c c c c c c c b b b b b b b b b a a a a a a a a 1 2 2 1 2 2 2 1 1 1 2 1 1 2 2 1 2 2 2 1 1 1 2 1 1 2 2 1 2 2 2 1 1 1 2 1
例1 21 B= 01 12 一 般而言 AB≠BA,即矩阵乘法不满足交换律, 但满足结合律 ABC=A(BC)=(AB)C
例1 = 0 1 0 1 0 1 A = 1 0 0 1 2 1 B = = 0 1 3 1 1 0 0 1 2 1 0 1 1 0 0 1 AB = = 1 0 1 0 1 0 2 1 2 0 1 1 0 0 1 1 0 0 1 2 1 BA 一般而言 AB BA, 即矩阵乘法不满足交换律, 但满足结合律 ABC = A(BC) =(AB)C
转置矩阵、共轭矩阵、转置共轭矩阵 A=[agjlnxm AT=[ajil mxn A*=[aj*]nxm (3.18) 如4】-公 列4a 如果 F=ABC…X 则 FH=(ABC...X)H=XH...CHBHA (3.19)
转置矩阵、共轭矩阵、转置共轭矩阵 A = [aij] nm AT = [aji] mn A* = [aij*] nm 例2 = 2 1 2 i i A = 2 2 1 i i A T − − = 2 1 2 i i A* − − = 2 2 1 i i A H (3.18) 如果 F = ABCX 则 FH = (ABCX)H = XHCHBHA (3.19)