Re: [理工] [線代] 99台大電機

看板Grad-ProbAsk作者 (AG)時間15年前 (2011/02/14 22:52), 編輯推噓3(305)
留言8則, 5人參與, 最新討論串2/2 (看更多)
※ 引述《compulsory (まけない!)》之銘言: : suppose that v,w,z are vector in R^n such that v is orthogonal to z and z is : orthogonal to w. Then : (a)For any orthogonal n*n matrix H,we have that Hz is orthogonal to both v & w : (b)v+w is orthogonal to z : (c)v is orthogonal to w : (d)For any orthogonal n*n matrix H, we have that Hv is orthogonal to z : 我知道b是對的 : c是錯的 : a d不太會選 a) 舉一個n = 2的情況為反例 let v = (1,0), z = (0,1), w = (2,0) H = [ 0 1 ] Hz = (1,0) 並沒有和 v,w 正交 [ 1 0 ] d) 我想是相同道理吧! -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 111.243.149.202

02/14 22:59, , 1F
感謝
02/14 22:59, 1F

02/14 23:11, , 2F
用幾何的角度來想, orthogonal matrix 就是旋轉的意思,
02/14 23:11, 2F

02/14 23:11, , 3F
轉個角度, 也許就不垂直了
02/14 23:11, 3F

02/15 00:01, , 4F
正交保角度 Hv Hz就會垂直
02/15 00:01, 4F

02/15 00:14, , 5F
樓上說的其實也是保內積
02/15 00:14, 5F

02/15 00:14, , 6F
嗯嗯, 一起轉某個角度, 相對好像沒轉一樣。
02/15 00:14, 6F

02/15 11:07, , 7F
哦哦~ 所以這題如果說是Hv正交Hz的話就是Ture囉? 是嗎?
02/15 11:07, 7F

02/15 12:18, , 8F
是的
02/15 12:18, 8F
文章代碼(AID): #1DMK6onT (Grad-ProbAsk)
文章代碼(AID): #1DMK6onT (Grad-ProbAsk)