similar to: FW: Re: symmetric matrix multiplication

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.

Hi Ted, yes this was the problem. Thank you very much. best idaios On Wed, Jan 9, 2013 at 4:51 PM, Ted Harding <Ted.Harding@wlandres.net>wrote: > Ah! You have aqssigned a parameter "equal.var=TRUE", and "equal.var" > is not a listed paramater for t.test() -- see ?t.test : > > t.test(x, y = NULL, > alternative = c("two.sided",

Hi Folks, [This is not unrelated to the current "vector of vectors" thread, but arises quite independently] Say I have a function f(x,y) which computes a value for scalar x and y; or, if either x=X or y=Y is a vector, a corresponding vector of values f(X,y) or f(x,Y) (with the usual built-in vectorisation of operations). Now I have X=(x.1,x.2,...,x.m) and Y=(y.1,y.2,...,y.n). I'm

When moderating this message just now I forwarded it to r-help-owner, for discussion. In reply to Roy's question, there is indeed nothing obvious which should "match a filter rule". However, the ETHZ spam filter is somewhat sensitive about gmail, regardless of true content, and there are 4 occurrences of "gmail.com", which may have been responsible for it. Looking at the

No. But it has not been posted either. You got that message because you sent your message to the wrong address. You should have sent it to r-help at r-project.org You had probably sent it to r-help-request at r-project.org which would have had the effect that the server would have tried to interpret the contents of you message as commands (e.g. to unsubscribe, change your subscription

Greetings All! As is often the case on this list, the answer may well be under my nose but I can't see it! I am looking for a "smart" way to do the following. Say I have a vector of values, X. I set up bins" for X, say with breaks at B = c(b1,b2,...,b11) covering the range of X, i.e. bins numbered 1:10. The value x is in bin i if B[i] < x <= B[i+1] What I seek is a

Greetings! For some reason I am not managing to work out how to do this (in principle) simple task! As a result of applying strsplit() to a vector of character strings, I have a long list L (N elements), where each element is a vector of two character strings, like: L[1] = c("A1","B1") L[2] = c("A2","B2") L[3] = c("A3","B3")

A quick question: Is there anywhere a listing of the RGB components of the named colours listed by colors()? For example, where would I find the RGB for "orange1" or "salmon"? When I look at an EPS file from R where I have used these colours, it seems that for: "salmon": 0.9804 0.5020 0.4471 rgb "orange1": 1 0.6471 0 rgb However, this is a tedious way

Greetings All. The function edit.data() allows a convenient spreadsheet-like view of a dataframe with too many rows/columns to fit on the screen (especially when there are many columns). Very useful when scanning through a dataset (row & column are conveniently identified by the labels at the side and above). However, there seens to be no option to set it "read-only" on start-up,

Greetings All. I want to do the following simple thing. I have defined a function med3x3() such that, given vectors X,Y, med3x3(X,Y) returns a 3x3 table where: Row 1: X > median(X) Row 2: X = median(X) Row 3: X < median(X) Col 1: Y < median(Y) Col 2: Y = median(Y) Col 3: Y > median(Y) (with intersections of these conditions for the individual cells). I can easily define fixed

Greetings All. Once again, I am probably missing something fairly accessible, but since I can't find it I'd welcome advice! I have a dataframe derived from a text file of data in tabular format. For one of the variables, say X, I want to select the subsets which in which X equals a particular value. Such values are given in the text file like: 2.3978953, and each such value will occurr

Greetings All. This is a somewhat generic query (I'm really asking on behalf of a friend who uses R on Windows, whereas I'm on Linux, but the same phenomenon appears on both). Say one has a largish dataframe -- call it "G" -- which in the case under discussion has 592 rows and 41 columns. The intention is to display the data by simply entering its name (G) as command. Say the

Greetings! I want to have the coefficients that R uses in shapiro.test() for the Shapiro-Wilk test for a prticular sample size, i.e. the a[i] in W = Sum(a[i]*x[i])/(Sum(x[i] - mean(x))^2) (where the x[i] are sorted). Two questions: Q1: Is there a readymade R function from which I can extract these? Q2: I was wondering if I might be able to modify the code for the function shapiro.test() so

Greetings All. My apologies for a question whose answer is probably readily available somewhere (for some interpetation of "somewhere") ... Say I have just typed (from a sheet of paper) several lines into the R command-line, and what I see is: > chisq.test(matrix(c(3,6,3,4,4, + 4,1,4,6,5, + 2,7,4,2,5, + 8,2,4,4,2, +

Greetings! I have just signed up to r-sig-fedora because I have installed Scientific Linux 6.2 (my first Red Hat based Linux since over 10 years ago ... ). I'm trying this for basically 2 reasons: first, I expect CERN and FermiLab should do a good job of maintaining their distribution, and in particular to take care of its compatibility with scientific software; second, because it still has

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

Greetings all! A recent news item got me thinking that a problem stated therein could provide a teasing little exercise in R programming. http://www.bbc.co.uk/news/uk-england-cambridgeshire-17680326 Cambridge University hosts first European 'maths Olympiad' for girls The first European girls-only "mathematical Olympiad" competition is being hosted by Cambridge

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

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

I would presume this is another manifestation of what I reported (reproduced below) on 2003-12-01. cajo.terbraak at wur.nl wrote: >Full_Name: cajo ter Braak >Version: 2.1.1 >OS: Windows >Submission from: (NULL) (137.224.10.105) > > ># I would like to attach the matrix C in the Rdata file; it is 50x50 and comes >from a geostatistical problem (spherical covariogram) >