similar to: Find A, given B where B=A'A

Dear R helpers, is there a function or way within R to solve A'A=S for A, where all matrices have p x p order and S is a variance-covariance matrix? Thank you, Ralf Engelhorn

It is not clear to me that one can. If the singular value decomposition of A is the triple product P d Q', then the singular value decomposition of A'A=S is Q d^2 Q'. The information about the orthonormal matrix P is lost, is it not? ********************************************************** Cliff Lunneborg, Professor Emeritus, Statistics & Psychology, University of Washington,

Hello, I have a short question about the prcomp function. First I cite the associated help page (help(prcomp)): "Value: ... SDEV the standard deviations of the principal components (i.e., the square roots of the eigenvalues of the covariance/correlation matrix, though the calculation is actually done with the singular values of the data matrix). ROTATION the matrix of variable loadings

In trying to install the pbatR package, I was greeted with the error Error: package 'tcltk' does not have a name space Execution halted Directly installing the package tcltk2 returned the following error: Loading required package: tcltk Error in firstlib(which.lib.loc, package) : Tcl/Tk support is not available on this system I have seen from previous posts that tcl/tk must be

Dear R-users, I computed determinant of a square matrix "var.r" using the SVD output: detr _ 1 d _ svd(var.r)$d for (i in 1:length(d)) { detr _ detr*d[i] } print(detr) 30.20886 BUT when I tried : det(var.r) I got : -30.20886 Is this because SVD output will only give absolute of the eigenvalues ?, If this is the case how can I get the original eigenvalues? Thanks, Agus

We get caught occasionally, and we all receive spam; sorry for the last one (on R-help). Of course, there will never be a 100% sure prevention... Question is what should happen when mail from R-help to an adressee is refused with the following message : At least I won't be able to easily send e-mail to them {and am not willing to use a non-easy way}.... ----- Transcript of session

The offset argument used in glm and other functions seems to have been removed from the argument list for coxph. I am wondering if there is a reason for this and if there is a possible work-around in order to produce a cox-ph object without fitting coefficients? Thanks, Mike

I have created a data frame using the read.table command. I want to be able to access the rows by the row name, or a vector of row names. I know that you can access columns by using the data.frame.name$col.name. Is there a way to access row names in a similar manner? [[alternative HTML version deleted]]

I am trying to preprocess a large dataset of affymetrix data. Creating an affybatch is not possible with the computer I am running it on, so I have used the justRMA command to run RMA. I have read the affy document describing the justRMA command and the help documentation but I am unclear as to whether this command uses median polish after normalization. I assume this is the case but would like

Hello List, i need help for eigen and svd functions. I have a non-symmetric square matrix. These matrix is not positive (some eigenvalues are negative). I want to diagonalise these matrix. So, I use svd and eigen and i compare the results. eigen give me the "good" eigenvalues (positive and negative). I compare with another software and the results are the same. BUT, when i use svd,

Hello, a. is there a possibility to obtain a distance matrix with the cosine between vectors?? hclust, hierclust, dist will not work and seem to be hard to extend. b. if there is not: Is the cosine between vectors implemented somewhere? Thanks for all hints and advice! Petra Steiner -------------- next part -------------- An HTML attachment was scrubbed... URL:

Hi all. I have an issue that I cannot resolve. I am trying to read in lots of data that are stored in xml files. But after I read them in and copy the relevant data, then remove the document etc, it doesn't free up the memory. When I monitor it in windows task manager the memory usage just climbs with each iteration until R crashes. I can replicate the problem with the small example:

I am trying to run a monte carlo process using snow with a MPI cluster. I have ~thirty processors to run the algorithm on and I want to run it 5000 times and take the average of the output. A very simple way to do this is to divide 5000 by the number of processors to get a number n and tell each processor to run the algorithm n times. I realize there are more efficient ways to manage the

I tried to reproduce a result from a former colleague which he got with S-plus bootstrap method. I don't have S-plus at hand. In R, there are 2 packages related to bootstrap method, bootstrap and boot. The former has a function called 'bootstrap' but this does not seem to conform either to the function used in S-plus nor to that described in MASS, 3d ed., p.144. The latter seems to be

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I'm trying to understand some C code in an R package I'm using. I'm address this question here as it's matrix algebra...and I'm no pro at that! the C command reads: double alpha = 1.0, beta = 0.0; dsyrk_("L", "N", nGenes, nGenes, & alpha, mat1, nGenes, & beta, mat2, nGenes); - From google,

I have a problem moving from multistratum aov analysis to lmer. My dataset has observations of ampl at 4 levels of gapf and 2 levels of bl on 6 subjects levels VP, with 2 replicates wg each, and is balanced. Here is the summary of this set with aov: >> summary(aov(ampl~gapf*bl+Error(VP/(bl*gapf)),hframe2)) > >Error: VP > Df Sum Sq Mean Sq F value Pr(>F) >Residuals

Hi All I am using the samba 3.0.14a RPMs installed on SuSE 9.2. I have a PDC running on one machine, using tdbsam as a backend - this has been running fine for months. I am not trying to set up a standalone server in another office, which should authenticate with the PDC using winbind, as per the "The 500-User office" chapter of samba by example :

I created a simple test to try and pinpoint my problem but nothing seems clear to me. I created a Thing model with fields { id (INT), date (DATE) } now when I try to create a new "thing" the date does not get stored, and no errors are reported. @myNewThing = Thing.new(:date => "2006-08-07") @myNewThing.save this results in a new record with a date of

Subj. says it. The patch contains several lines complaining about "No newline". After removing these the patch was applicable. -- Dipl.-Math. Wilhelm Bernhard Kloke Institut fuer Arbeitsphysiologie an der Universitaet Dortmund Ardeystrasse 67, D-44139 Dortmund, Tel. 0231-1084-257 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel mailing list -- Read

I''m just getting used to using HABTM structures. Something I''m trying to do now is create a site that has "sections" each section then could have a sub "section". So I built a "sections" table and in the model I included the line "has_and_belongs_to_many :sections" I also made a table called "sections_sections" to build the