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Functions for Sum of determinants of ranges of matrix subsets
2 messages · John James, Dennis Murphy
Hi: Try this:
z <- matrix(rnorm(100), nrow = 10) sum(sapply(seq_len(nrow(z)), function(k) det(z[-k, -k])))
[1] 1421.06 where
sapply(seq_len(nrow(z)), function(k) det(z[-k, -k]))
[1] 432.11613 81.65449 516.95791 54.72775 804.32097 -643.35436 [7] -411.15932 394.18780 84.13173 107.47665 HTH, Dennis
On Tue, Aug 2, 2011 at 5:18 AM, john james <dntssa at yahoo.com> wrote:
Dear R-help list, Pls I have this problem. Suppose I have a matrix of size nxn say, generated as follows z<-matrix(rnorm(n*n,0,1),nrow=n) I want to write a function such that for i in 1:n, I will remove the rows and columns corresponding to i (so, will be left with n-1*n-1 submatrix in each cases). Now I need the sum of the determinant of each of this submatrices. As an example, if n=3, it means I will have det(1strow and 1stcolum removed) + det(2ndrow and 2ndcolum removed) + det(3rdrow and 3rdcolum removed). Any help will be appreciated. Thanks John ? ? ? ?[[alternative HTML version deleted]]
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