search for: vech

Let say i have a square matrix and applied the 'vech' operator to stack the lower triangular elements into a vector: > Mat <- matrix(1:25, 5) > Mat ? ? ?[,1] [,2] [,3] [,4] [,5] [1,] ? ?1 ? ?6 ? 11 ? 16 ? 21 [2,] ? ?2 ? ?7 ? 12 ? 17 ? 22 [3,] ? ?3 ? ?8 ? 13 ? 18 ? 23 [4,] ? ?4 ? ?9 ? 14 ? 19 ? 24 [5,] ? ?5 ? 10 ? 15 ? 20 ? 25 > Mat[l...

Dear R-list members, Just wondering if there is any way to compute the duplication matrix in R. I tried to search for it but only found functions "xpnd" and "vech". Basically for a symmetric n by n matrix A, the duplication matrix D_n is a matrix of dimension n^2 by n(n+1)/2 such that D_n vech(A)= c(A), where c(A) just vectorizes A. The duplication matrix is defined on page 49 of the book "Matrix differential calculus with applications in stati...

Can anyone please tell whether there is any R function to act as "VEC" and "VECH" operator on Matrix? Yes of course, I can write a user-defined-function for that or else, I can put dim(mat) <- NULL. However I am looking for some R function. Your help will be highly appreciated. Regards, -- View this message in context: http://www.nabble.com/VEC-Operator-in-R-tp201362...

...objects to cluster") : argument is of length zero I understand that the documentation says that the matrix ' d: a dissimilarity structure as produced by 'dist''. Does that mean that I need to convert it into a lower triangle matrix? I also tried: newclust = hclust(vech(distmat)) but this gave a similar error. Where am I going wrong? Also, will hclust be able to handle 'NA' in the dissimilarity matrix? many thanks, Tim --------------------------------- [[alternative HTML version deleted]]

...Burns" <pburns@pburns.seanet.com> To: "megh" <megh700004@yahoo.com> Cc: r-help@r-project.org Date: Thu Oct 23 13:24:49 CDT 2008 Subject: Re: [R] VEC Operator in R For 'VEC' you may not need to do anything -- in a lot of circumstances it will just work. For 'VECH' you can write a function using the 'lower.tri' function. But it seems to me that the assumption behind your question is that a simple function that someone else has written is going to be better than a simple function that you write.  Not true (barring bugs). R is egalitarian -- your...

...e. In UK this happens at 1am and on that day there is no such thing as 01:05, etc., see eg https://www.timeanddate.com/time/change/uk/london In your time zone this probably happens at 2am. Georgi Boshnakov ------------------------------ Message: 7 Date: Thu, 26 Jan 2017 11:02:06 +0100 From: rob vech <rob.vech87 at gmail.com> To: r-devel at r-project.org Subject: [Rd] strptime bug Message-ID: <70325e6b-6d54-8172-3915-bbfc8d5cd837 at gmail.com> Content-Type: text/plain; charset="UTF-8" Dear developer list, I want to submit the following problem that seems like a bug, as co...