Displaying 20 results from an estimated 5000 matches similar to: "symmetric matrix multiplication"
2011 Oct 23
0
FW: Re: symmetric matrix multiplication
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
2005 Jul 04
1
eigen of a real pd symmetric matrix gives NaNs in $vector (PR#7987)
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)
> rm(list=ls(all=TRUE))
> load(file= "test.eigen.Rdata")
> ls()
[1] "C" "eW"
>
> sym.check = max(abs(C - t(C))) # should
2012 Mar 19
2
hypergeometric function in ‘ mvtnorm’
Is there any way to know how the "dmvt" function computes the hypergeometric
function needed in the calculation for the density of multivariate t
distribution?
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2005 Jul 04
0
eigen of a real pd symmetric matrix gives NaNs in $vector (PR#7989)
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)
>
2013 Jun 18
1
eigen(symmetric=TRUE) for complex matrices
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
2011 Mar 27
1
pmt
I am working with the pmt function in the {mnormt} package, and i am getting
negative values returned. the following is an example of one of my outputs:
pmt(x = c(3.024960, -1.010898), mean = c(21.18844, 21.18844), S =
matrix(c(.319,.139,.139,0.319), 2, 2),df = 42)
# -6.585641e-18
Any help on why i'm getting negative numbers would be very much appreciated.
THanks!
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2007 Nov 29
1
?eigen documentation suggestion
from ?eigen
symmetric: if 'TRUE', the matrix is assumed to be symmetric (or
Hermitian if complex) and only its lower triangle is used. If
'symmetric' is not specified, the matrix is inspected for
symmetry.
I think that could mislead a naive reader as it suggests that, with symmetric=TRUE,
the result of eigen() (vectors and values) depends only on
2011 Dec 22
1
try to silence errors
I am trying to use the dmt function in the package {mnormt}. Throughout my
algorithm, the covariance matrix is sometime calculated to be singular.
When attempting to calculate the dmt function with a covariance that is not
positive definite, I would like it to return Inf or NaN instead of an error
message.
I have been using the try function, however it is not yeilding the desired
result. (I did
2007 Mar 16
1
error code 5 from Lapack routine 'dsyevr'
While using the rmvnorm function, I get the error:
Error in eigen(sigma, sym = TRUE) : error code 5 from Lapack routine
'dsyevr'
The same thing happens when I try the eigen() function on my covariance
matrix. The matrix is a symmetric 111x111 matrix. Well, it is almost
symmetric; there are slight deviations from symmetry (the largest is
3e-18). I have this in an MCMC loop, and it
2009 Jul 23
2
SystemFit
Hi,
I have two products which are substitudes. I try to fix a system as below to
mydata.
Demand1 = A1 -B1*Price1 + C1*Price2
Demand2 = A2 +B2*Price1 - C2*Price2
I would expect C1 & B2 to be symmetric, If they are truly substitude. How
can I enforce this symmetry when creating a system of equations via
SystemFit ?
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2011 Nov 16
2
Conversion of symmetry matrix into a vector
Dear R users,
I am not good in R-language programming. So, i need your help.
I want to convert my lower-triangle value of symmetry matrix into a vector with their row and column name.
I found a function called "sm2vec" in "corpcor" package but it give only a vector of values but not row and column names. But i also want ROW and COLUMN name together with their corresponding
2005 May 01
2
eigen() may fail for some symmetric matrices, affects mvrnorm()
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
2003 Nov 04
2
real eigenvectors
Hello list,
Sorry, these questions are not directly linked to R.
If I consider an indefinte real matrix, I would like to know if the
symmetry of the matrix is sufficient to say that their eigenvectors are real ?
And what is the conditions to ensure that eigenvectors are real in the case
of an asymmetric matrix (if some conditions exist)?
Thanks in Advance,
St?phane DRAY
2011 Sep 12
2
1 not equal to 1, and rep command
Hi
I need to use rep() to get a vector out, but I have spotted something very
strange. See the reproducible example below.
N <- 79
seg <- 5
segN <- N / seg # = 15.8
d1 <- seg - ( segN - floor(segN) ) * seg
d1 # = 1
rep(2, d1) # = numeric(0), strange - why doesn't it print one "2"?
rep(2, 1) # 2, ok
rep(2, d1 / 1,1) # 2, this
2009 Oct 12
1
unexpected behaviour of isSymmetric() (PR#14000)
Full_Name: Mike Danilov
Version: 2.9.0
OS: Fedora Core 9
Submission from: (NULL) (142.103.121.198)
When checking for the symmetry of a matrix, function isSymmetric.matrix() gets
confused by the discrepancy of colnames/rownames if its argument. See the code
snippet below. Perhaps it's a problem of the matrix product which copies
colnames of the first argument but not the rownames of the
2011 Feb 04
2
always about positive definite matrix
1. Martin Maechler's comments should be taken as replacements
for anything I wrote where appropriate. Any apparent conflict is a
result of his superior knowledge.
2. 'eigen' returns the eigenvalue decomposition assuming the
matrix is symmetric, ignoring anything in m[upper.tri(m)].
3. The basic idea behind both posdefify and nearPD is to compute
the
2006 Sep 26
2
about the determinant of a symmetric compound matrix
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 =
2010 Nov 08
1
Exponent of sqr symmetric matrix
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
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2011 Apr 06
1
Creating a symmetric contingency table from two vectors with different length of levels in R
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"
2006 Jun 15
2
Problem on Matrix multiplication
Dear all r-users,
I am getting a big problem with matrix multiplication
suppose I have,
> weight
Weight
1 1067640
2 8871500
3 42948778
4 127583735
5 22000000
6 44000000
7 56850000
8 23805662
and,
> s
a b c d e
f g h
a 402493.18 -133931.62 461483.3 -94042.86 674493.8