Displaying 20 results from an estimated 7000 matches similar to: "A question on orthogonal basis vectors"
2008 Nov 03
1
qr() and Gram-Schmidt
Hi,
Why the qr() produces a negative Q compared with Gram-Schmidt? (note
example below, except Q[2,3])
Here is an example, I calculate the Q by Gram-Schmidt process and
compare the output with qr.Q()
a <- c(1,0,1)
b <- c(1,0,0)
c <- c(2,1,0)
x <- matrix(c(a,b,c),3,3)
##########################
# Gram-Schmidt
##########################
A <- matrix(a,3,1)
q1 <-
2003 Sep 01
1
Gram-Schmidt orthonormal factorization
Hi:
Does R have a function as gsorth is SAS, that perform a the Gram-Schmidt
orthonormal factorization of the m ?n matrix A, where m is greater than or
equal to n? That is, the GSORTH subroutine in SAS computes the
column-orthonormal m ?n matrix P and the upper triangular n ?n matrix T such
that A = P*T.
or any other version of Gram-Schmidt orthonormal factorization?
I search the help, but I
2004 Feb 23
2
orthonormalization with weights
Hello List,
I would like to orthonormalize vectors contained in a matrix X taking into
account row weights (matrix diagonal D). ie, I want to obtain Z=XA with
t(Z)%*%D%*%Z=diag(1)
I can do the Gram-Schmidt orthogonalization with subsequent weighted
regressions. I know that in the case of uniform weights, qr can do the
trick. I wonder if there is a way to do it in the case of non uniform
2012 Mar 15
6
Generation of correlated variables
Hi everyone.
Based on a dependent variable (y), I'm trying to generate some independent
variables with a specified correlation. For this there's no problems.
However, I would like that have all my "regressors" to be orthogonal (i.e.
no correlation among them.
For example,
y = x1 + x2 + x3 where the correlation between y x1 = 0.7, x2 = 0.4 and x3 =
0.8. However, x1, x2 and x3
2008 Sep 05
1
Orthogonalization algorithms
Hi,
I have eight vectors that I would like to orthogonalize preferably
using R. The vectors are of considerable length, however due to their
nature I know they satisfy the conditions needed to apply the
Gram-Schmidt algorithm. Before I embark on some R coding, I wanted to
check that there is no facility / function already around that computes
the orthogonalized set of vectors? I have performed
2006 Oct 18
1
Calculation of Eigen values.
Dear all R users,
Can anyone tell me to calculate Eigen value of any real symmetric matrix
which algorithm R uses? Is it Jacobi method ? If not is it possible to get
explicit algorithm for calculating it?
Thanks and regards,
Arun
[[alternative HTML version deleted]]
2004 May 06
5
Orthogonal Polynomial Regression Parameter Estimation
Dear all,
Can any one tell me how can i perform Orthogonal
Polynomial Regression parameter estimation in R?
--------------------------------------------
Here is an "Orthogonal Polynomial" Regression problem
collected from Draper, Smith(1981), page 269. Note
that only value of alpha0 (intercept term) and signs
of each estimate match with the result obtained from
coef(orth.fit). What
2016 Oct 24
3
typo or stale info in qr man
man for `qr` says that the function uses LINPACK's DQRDC, while it in
fact uses DQRDC2.
```
The QR decomposition of the matrix as computed by LINPACK or LAPACK.
The components in the returned value correspond directly to the values
returned by DQRDC/DGEQP3/ZGEQP3
```
2002 Oct 08
2
Orthogonal Polynomials
Looking to the wonderful statistical advice that this group can offer.
In behavioral science applications of stats, we are often introduced to
coefficients for orthogonal polynomials that are nice integers. For
instance, Kirk's experimental design book presents the following
coefficients for p=4:
Linear -3 -1 1 3
Quadratic 1 -1 -1 1
Cubic -1 3 -3 1
In R orthogonal
2009 Aug 20
4
Principle components analysis on a large dataset
Dear Sirs:
Please pardon me I am very new to R. I have been using MATLAB.
I was wondering if R would allow me to do principal components analysis on a
very large
dataset.
Specifically, our dataset has 68800 variables and around 6000 observations.
Matlab gives "out of memory" errors. I have tried also doing princomp in
pieces, but this does not seem to quite work for our approach.
2016 Feb 27
2
Possible soundness issue with available_externally (split from "RFC: Add guard intrinsics")
On Fri, Feb 26, 2016 at 8:43 PM, Chandler Carruth <chandlerc at google.com>
wrote:
> On Fri, Feb 26, 2016 at 8:40 PM Xinliang David Li <xinliangli at gmail.com>
> wrote:
>
>> On Fri, Feb 26, 2016 at 8:30 PM, Chandler Carruth <chandlerc at google.com>
>> wrote:
>>
>>> On Fri, Feb 26, 2016 at 8:15 PM Hal Finkel <hfinkel at anl.gov> wrote:
2003 Feb 14
2
How to solve A'A=S for A
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,
2007 Aug 16
4
Linear models over large datasets
I'd like to fit linear models on very large datasets. My data frames
are about 2000000 rows x 200 columns of doubles and I am using an 64
bit build of R. I've googled about this extensively and went over the
"R Data Import/Export" guide. My primary issue is although my data
represented in ascii form is 4Gb in size (therefore much smaller
considered in binary), R consumes about
2008 Jul 24
2
What is wrong with this contrast matrix?
Dear all,
I am fitting a multivariate linear model with 7 response variables and 1 explanatory variable.
The following matrix P:
P <- cbind(
c(1,-1,0,0,0,0,0),
c(2,2,2,2,2,-5,-5),
c(1,0,0,-1,0,0,0),
c(-2,-2,0,-2,2,2,2),
c(-2,1,0,1,0,0,0),
c(0,-1,0,1,0,0,0))
should consist of orthogonal elements (as can be shown using %*% on the individual columns).
However, when I use
2007 Feb 13
1
Questions about results from PCAproj for robust principal component analysis
Hi.
I have been looking at the PCAproj function in package pcaPP (R 2.4.1) for
robust principal components, and I'm trying to interpret the results. I
started with a data matrix of dimensions RxC (R is the number of rows /
observations, C the number of columns / variables). PCAproj returns a list
of class princomp, similar to the output of the function princomp. In a
case where I can
2016 Feb 27
0
Possible soundness issue with available_externally (split from "RFC: Add guard intrinsics")
----- Original Message -----
> From: "Xinliang David Li" <xinliangli at gmail.com>
> To: "Chandler Carruth" <chandlerc at google.com>
> Cc: "Hal Finkel" <hfinkel at anl.gov>, "llvm-dev"
> <llvm-dev at lists.llvm.org>, "Philip Reames"
> <listmail at philipreames.com>, "Duncan P. N. Exon Smith"
2016 Feb 27
2
Possible soundness issue with available_externally (split from "RFC: Add guard intrinsics")
On Fri, Feb 26, 2016 at 8:57 PM, Hal Finkel <hfinkel at anl.gov> wrote:
>
>
> ------------------------------
>
> *From: *"Xinliang David Li" <xinliangli at gmail.com>
> *To: *"Chandler Carruth" <chandlerc at google.com>
> *Cc: *"Hal Finkel" <hfinkel at anl.gov>, "llvm-dev" <llvm-dev at lists.llvm.org>,
>
2010 Jan 16
2
La.svd of a symmetric matrix
Dear R list users,
the singluar value decomposition of a symmetric matrix M is UDV^(T), where U = V.
La.svd(M) gives as output three elements: the diagonal of D and the two orthogonal matrices u and vt (which is already the transpose of v).
I noticed that the transpose of vt is not exactly u. Why is that?
thank you for your attention and your help
Stefano
AVVISO IMPORTANTE: Questo messaggio di
2003 Feb 28
1
How to generate multiple squre Orthogonal matrices?
Hey, all
Will you please tell me how to generate multiple
square orthogonal matrices for data transformation usage?
Thanks.
Fred
2011 Aug 09
1
rgl how to plot a cylinder like arrow3d?
Dear List,
I'm trying to draw vector in XYZ with rgl under use of a cylinder3d.
Therefore I scale and rotate a basis-cylinder).
However, somehow the rotation is wrong as
verified by overplotting arrow3d().
Where is my mistake?
library(heplots)
library(rgl)
# ... 2 vectors
data=data.frame(row.names=c('X','Y','Z'), x1=c(2,1,5),y=c(4,3,2))