[理工] [工數] [矩陣] 正交

看板Grad-ProbAsk作者 (阿Ken)時間14年前 (2010/03/22 22:40), 編輯推噓9(9016)
留言25則, 9人參與, 最新討論串1/1
Is the following matrix orthogonal? Why? (10%) [ 1 ] [ --- - √2/3 0 ] [ √3 ↓ ] [ (-√2/√3) ] [ ] [ 1 1 -1 ] [ --- --- --- ] [ √3 √6 √2 ] [ ] [ ] [ 1 1 1 ] [ --- --- --- ] [ √3 √6 √2 ] ---------------------------------------------- 我計算過程 [ 2 -√2 √2 ] [ ---- ----- ---- ] [ √12 √6 √6 ] [ ] [ ] [ -2 1 -2 ] [ --- ---- ---- ] [ √6 √6 √6 ] [ ] [ -2 2 ] [ 0 --- ---- ] [ √18 √18 ] A^-1 = ------------------------------- <===(計算冗長,算到有點恍神 |A| = 1 根據正交定義A^T = A^-1 故 (1)此矩陣不為正交 (2)因為A^T≠A^-1 請問有其他方法算這題的反矩陣嗎? 還有我的答案(1)(2)的觀念是對的嗎?? 麻煩各位幫忙了謝謝 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 220.139.149.158

03/22 22:41, , 1F
水球怎麼丟.
03/22 22:41, 1F

03/22 22:43, , 2F
我怎麼算是有正交@@?
03/22 22:43, 2F

03/22 22:44, , 3F
而且你真的有把A^T算出來 還有A^-1算出來去相比嗎?
03/22 22:44, 3F

03/22 22:44, , 4F
算(A^T)A=I 為正交
03/22 22:44, 4F

03/22 22:45, , 5F
下面過程是我自己寫的,想要請教觀念與解題過程
03/22 22:45, 5F

03/22 22:45, , 6F
另外一個比較快的判別方法就是把矩陣看成三條行向量
03/22 22:45, 6F

03/22 22:46, , 7F
確認每一條行向量都是單位向量 且兩兩互相垂直 及正交
03/22 22:46, 7F

03/22 22:46, , 8F
然後行向量兩兩相乘總合為1
03/22 22:46, 8F

03/22 22:47, , 9F
我有把A^T算出來,沒打到上面抱歉@@
03/22 22:47, 9F

03/22 22:48, , 10F
內積=0 不就可以看的嗎??
03/22 22:48, 10F

03/22 22:51, , 11F
shi....看成是orthonormal了 那這樣不用是單位向量 sry
03/22 22:51, 11F

03/22 22:53, , 12F
我用A^-1去算好像自找麻煩了...算超久
03/22 22:53, 12F

03/22 22:54, , 13F
推內積
03/22 22:54, 13F

03/22 22:56, , 14F
請問a大的意思跟k大的意思是一樣嗎?? 內積=0
03/22 22:56, 14F

03/22 23:01, , 15F
請問是指(A^T)˙A=0的意思嗎??
03/22 23:01, 15F

03/22 23:03, , 16F
03/22 23:03, 16F

03/22 23:10, , 17F
謝謝sq大k大shiny大a大ntust大,topee一起加油,按w
03/22 23:10, 17F

03/22 23:11, , 18F
那有好幾百個人回你要怎麼辦XD
03/22 23:11, 18F

03/22 23:16, , 19F
怎麼像作者丟水球阿~
03/22 23:16, 19F

03/22 23:16, , 20F
03/22 23:16, 20F

03/22 23:19, , 21F
有人願意替我解答只有感激不盡:)
03/22 23:19, 21F

03/22 23:23, , 22F
因為A^T = A^-1 所以(A^T)(A) = I
03/22 23:23, 22F

03/22 23:29, , 23F
直接看有沒有行orthonormal 應該就好了?
03/22 23:29, 23F

03/23 01:12, , 24F
請問看有沒有行orthonormal是sq大 說的解法嗎?還是?
03/23 01:12, 24F

03/23 01:13, , 25F
謝謝WinAVI大
03/23 01:13, 25F
文章代碼(AID): #1Bfu5gg6 (Grad-ProbAsk)