2018-11-20
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矩陣對(duì)角元素相關(guān)運(yùn)算
例如要取一個(gè)方陣的對(duì)角元素,
> A=matrix(1:16,nrow=4,ncol=4)
> A
[,1] [,2] [,3] [,4]
[1,] 1 5 9 13
[2,] 2 6 10 14
[3,] 3 7 11 15
[4,] 4 8 12 16
> diag(A)
[1] 1 6 11 16
對(duì)一個(gè)向量應(yīng)用 diag()函數(shù)將產(chǎn)生以這個(gè)向量為對(duì)角元素的對(duì)角矩陣,例如:
> diag(diag(A))
[,1] [,2] [,3] [,4]
[1,] 1 0 0 0
[2,] 0 6 0 0
[3,] 0 0 11 0
[4,] 0 0 0 16
對(duì)一個(gè)正整數(shù) z 應(yīng)用 diag()函數(shù)將產(chǎn)生以 z 維單位矩陣,例如:
> diag(3)
[,1] [,2] [,3]
[1,] 1 0 0
[2,] 0 1 0
[3,] 0 0 1






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