※ 引述《KAINTS (RUKAWA)》之銘言：
: Let S be a nonempty set of vectors in R^n,
: and let v be in R^n. The spans of S and
: S or {v} are equal iif v is in S.
: ans:F why????
if span S ≠ S, then span S = {v} have only one element
=> span S = {v} = {0}
by the hypothis, we know that S ≠ span{S} = {v} = {0}
=> S has nonzero vector(s) , let S = {v1,...,vr}
but {0} = span S = span {v1,...,vr} ≠ {0} (→←)
if span S ≠ {v}, then span S = S
(1) S = R^n
in this case, v€S, but
(2) S = {0}
in this case, v does not have to be in S
: http://imgur.com/7zog8
: (F) 54. 變成rref 不是只有一種方法嗎??? 那個P不是只有一種嗎?
: P[A b]=[R c]
這題的陷阱應該在於sequence
就是說P是唯一沒錯，但是我做列運算的順序卻可以有很多種順序
我覺得是沒什麼營養的題目...
: (T) 56.這題為什麼是對..
: 感謝大大回答
我不太懂什麼叫scaling operation，或許是我才疏學淺
然後還有forward pass of Gaussian Elimination是什麼意思
猜了一下，scaling operation應該是對某列縮放的那一型列運算
forward pass of Gaussian Elimination應該是沒有要求要rref
所以每一列的pivot(最左邊的非零項)不一定要1
所以可以不用用到縮放(scaling operation)
除非課本有特地提到這些單字的意思，不然這題也沒什麼營養..
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◆ From: 220.141.9.112
※ 編輯: ILzi 來自: 220.141.9.112 (07/02 23:28)