search for: symmetrical

Just to avoid possible confusion, let me correct a typo (at step [2] in the example below). Apologies! -----FW: <XFMail.111023084327.ted.harding at wlandres.net>----- Date: Sun, 23 Oct 2011 08:43:27 +0100 (BST) Sender: r-help-bounces at r-project.org From: (Ted Harding) <ted.harding at wlandres.net> To: r-help at r-project.org Subject: Re: [R] symmetric matrix multiplication On

R-3.0.1 rev 62743, binary downloaded from CRAN just now; macosx 10.8.3 Hello, eigen(symmetric=TRUE) behaves strangely when given complex matrices. The following two lines define 'A', a 100x100 (real) symmetric matrix which theoretical considerations [Bochner's theorem] show to be positive definite: jj <- matrix(0,100,100) A <- exp(-0.1*(row(jj)-col(jj))^2) A's being

Hi all, Recently our statistics students noticed that their Gibbs samplers were crashing due to some NaNs in some parameters. The NaNs came from mvrnorm (Ripley & Venables' MASS package multivariate normal sampling function) and with some more investigation it turned out that they were generated by function eigen, the eigenvalue computing function. The problem did not seem to happen

Greetings, I have a seemingly simple task which I have not been able to solve today. I want to construct a symmetric matrix of arbtriray size w/o using loops. The following I thought would do it: p <- 6 Rmat <- diag(p) dat.cor <- rnorm(p*(p-1)/2) Rmat[outer(1:p, 1:p, "<")] <- Rmat[outer(1:p, 1:p, ">")] <- dat.cor However, the problem is that the matrix

At 01:37 PM 5/10/00 +0200, ralle wrote: >Hi, >I have a problem understanding what is going on with eigen() for >nonsymmetric matrices. >Example: >h<-rnorm(6) >> dim(h)<-c(2,3) >> c<-rnorm(6) "c" is not a great choice of identifier! >> dim(c)<-c(3,2) >> Pi<-h %*% c >> eigen(Pi)$values >[1] 1.56216542 0.07147773 These could

I use a solution to crypt a string that I found using OpenSSL. But the crypted string becomes very long, too long for a varchar 255 to hold it. What can I do to make it shorter? Or should I just use text as column in the mysql db? public_key_file = ''lib/public.pem'' public_key = OpenSSL::PKey::RSA.new(File.read(public_key_file)) @encrypted_string =

So many matrices are square symmetrical (i.e. variance-covariance matrices), is there any way to get R to split the matrix on its diagonal and just return one diagonal? So if I have mat<-matrix(c(1,4,3,4,1,2,3,2,1), nrow = 3, ncol=3, byrow=TRUE) is there anyway to get the lower right diagonal instead of the entire symmetri...

I have a symmetric matrix B (17x17), and a (17x17) square matrix A. If do the following matrix multiplication I SHOULD get a symmetric matrix, however i don't. The computation required is: C = t(A)%*%B%*%A here are some checks for symmetry > (max(abs(B - t(B)))) [1] 0 > C = t(A)%*%B%*%A > (max(abs(C - t(C)))) [1] 3.552714e-15 Any help on the matter would be very much appreciated.

Dear all, I encounter some covariance matrix with quite small eigenvalues (around 1e-18), which are smaller than the machine precision. The dimension of my matrix is 17. Here I just fake some small matrix for illustration. a<-diag(c(rep(3,4),1e-18)) # a matrix with small eigenvalues b<-matrix(1:25,ncol=5) # define b to get an orthogonal matrix b<-b+t(b) bb<-eigen(b,symmetric=T)

Hello, I have a problem with a Grandstream being behind a symmetric nat. The box which does the nat is a german "Fritz Box". This one does nat for the internal network. In the internal network is a Granstream BudgeTone 100. The nat router has a dial-up connection, so ip changes on every dial-in. |------------| |------------| |--------| |Grandstream

Dear R community, is there an easy way to convert an adjacency list (or a data-frame) to a non-symmetric matrix? The adjacency list has the following form: person group 1 Sam a 2 Sam b 3 Sam c 4 Greg a 5 Tom b 6 Tom c 7 Tom d 8 Mary b 9 Mary d I need the data in a matrix with persons as rows and groups as columns: a b c d Sam 1 1 1 0 Greg 1 0 0 0 Tom 0 1 1 1 Mary 0 1 0 1 I know that there

Hi, It is my understanding that the eigenvectors of a circulant matrix are given as follows: 1,omega,omega^2,....,omega^{p-1} where the matrix has dimension given by p x p and omega is one of p complex roots of unity. (See Bellman for an excellent discussion on this). The matrix created by the attached row and obtained using the following commands indicates no imaginary parts for the

HI, I am really messing up to make a symmetrical matrix using upper.tri() & lower.tri() function. Here is my code:   > set.seed(1) > mat = matrix(rnorm(25), 5, 5) > mat            [,1]       [,2]       [,3]        [,4]        [,5] [1,] -0.6264538 -0.8204684  1.5117812 -0.04493361  0.91897737 [2,]  0.1836433  0.4874291  0.3898432 -0.0...

Hi, I am using eigen to get an eigen decomposition of a square, symmetric matrix. For some reason, I am getting a column in my eigen vectors (the 52nd column out of 601) that is a column of all NAs. I am using the option, symmetric=T for eigen. I just discovered that I do not get this behavior when I use the option EISPACK=T. With EISPACK=T, the 52nd eigenvector is (up to rounding error) a

Dear R users, even if this question is not related to an issue about R, probably some of you will be able to help me. I have a square matrix of dimension k by k with alpha on the diagonal and beta everywhee else. This symmetric matrix is called symmetric compound matrix and has the form a( I + cJ), where I is the k by k identity matrix J is the k by k matrix of all ones a = alpha - beta c =

Here's an easy question: I'd like to convert a symmetric matrix to a vector composed of the upper.tri() part of it plus the diagonal, and convert it back again. What's the best way to achieve this? I'm wondering if there are some built in functions to do this easily. I can encode fine: v <- c(diag(A),A[upper.tri(A)]) but I don't see an easy way to recover A from v

Hello, How can I create a symmetric contingency table from two categorical vectors having different length of levels? For example one vector has 98 levels TotalData1$Taxa.1 [1] "Aconoidasida" "Actinobacteria (class)" "Actinopterygii" "Alphaproteobacteria" [5] "Amoebozoa"

Dear R experts, I really have difficulty when I try to deal with this question. suppose X is a square symmetric matrix. The exponent of X is defined by the matrix limit as following: exp(X) = lim (I + X/n)^n, note: the limit is from n to infinite. How can I write R function for the above? Thank you very much -- View this message in context:

I have a people table: CREATE TABLE people ( id int(10) unsigned NOT NULL auto_increment, first_name varchar(75) default NULL, middle_name varchar(75) default NULL, last_name varchar(75) default NULL, PRIMARY KEY (id) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1272 ; and a people_people table: CREATE TABLE people_people ( person_id int(11) unsigned NOT NULL,

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I'm generating a symmetric correlation matrix using a data matrix as input: mat <- cor(data.mat) My question is: Is there a more memory efficient way to store this data? For instance, since: all(mat == t(mat)) every value is duplicated, and I should be able to almost half the memory usage for large matrices. Any thoughts/comments? Cheers,