作者xx52002 (冰清影)
看板Math
标题Re: [线代] 帮忙解一下!!
时间Tue Mar 1 00:13:56 2011
※ 引述《a520683 (小YA)》之铭言：
: Prove that the produce of two upper triangular matrix is upper triangular.
令A,B均为上三角 C=AB
则对所有i>j, a_ij=b_ij=0 (上三角定义)
要证对所有i>j, c_ij=0
给定i > j
n
c_ij = Σ a_ik * b_kj
k=1
= a_ii * b_ij + ... + a_in * b_nj (因为a_i1 = ... = a_i(i-1) = 0)
= 0 (因为b_ij = ... = b_nj = 0)
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1F：→ sardine :....这个人在洗文章... 你的好心被浪费了 03/01 00:20
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3F：→ a520683 :感谢你喔^^ 03/01 13:41