Displaying 19 results from an estimated 19 matches similar to: "Matrix multiplication"
2008 Aug 08
3
Multivariate regression with constraints
Hi all,
I am running a bivariate regression with the following:
p1=c(184,155,676,67,922,22,76,24,39)
p2=c(1845,1483,2287,367,1693,488,435,1782,745)
I1=c(1530,1505,2505,204,2285,269,1271,298,2023)
I2=c(8238,6247,6150,2748,4361,5549,2657,3533,5415)
R1=I1-p1
R2=I2-p2
x1=cbind(p1,R1)
y1=cbind(p2,R2)
fit1=lm(y1~-1+x1)
summary(fit1)
Response 2:
Coefficients:
Estimate Std. Error t value
2008 Aug 04
2
Multivariate Regression with Weights
Hi all,
I'd like to fit a multivariate regression with the variance of the error term porportional to the predictors, like the WLS in the univariate case.
y_1~x_1+x_2
y_2~x_1+x_2
var(y_1)=x_1*sigma_1^2
var(y_2)=x_2*sigma_2^2
cov(y_1,y_2)=sqrt(x_1*x_2)*sigma_12^2
How can I specify this in R? Is there a corresponding function to the univariate specification lm(y~x,weights=x)??
2008 Jul 30
2
Sampling two exponentials
Hi all,
I am going to sample two variables from two exponential distributions, but I want to specify a covariance structure between these two variables. Is there any way to do it in R? Or is there a "Multivariate Exponential" thing corresponding to the multivariate normal? Thanks in advance.
Sincerely,
Yanwei Zhang
Department of Actuarial Research and Modeling
Munich Re America
Tel:
2008 Aug 07
1
Covariance matrix
Hi all,
Assume I have a random vector with four variables, i.e. A=(a,b,c,d). I am able to get the covariance matrix of vector A, but how can I get the covariance matrix of vector B=(a,c,b,d) by manipulating the corresponding covariance matrix of A? Thanks.
Sincerely,
Yanwei Zhang
Department of Actuarial Research and Modeling
Munich Re America
Tel: 609-275-2176
Email:
2008 Aug 07
4
Switch two rows in a matrix
Hi all,
I have a 4 by 4 matrix, and I want to switch row 2 and row 3 first, then switch column 2 and column 3. Is there an easy way to do it?
The following is a tedious way to get what I want. But I wonder if there is a way to simplify this.
> a=matrix(rnorm(16),4,4)
> a
[,1] [,2] [,3] [,4]
[1,] 0.33833811 -0.9422273 -0.06181611 -1.8346134
[2,] -0.68167996
2008 Aug 12
1
VAR question
Hi all,
I got another VAR question here and really appreciate if somebody would help me out :)
I have five time series, say A,B,C,D,E. My objective is to predict the series A using the rest, that is, B, C, D and E. A Vector Autoregression Model should work here. But first of all, I should select which series of B, C, D and E to be include in the VAR model, as well as the number of lags. I wonder
2008 Jul 25
3
Numerical question
Hi all,
I have n independent variables A_1, A_2, A_3,......,A_n, and each with known variances var(A_1), var(A_2),..., but unknown mean. How can I get the approximation of the variance of the product of the variables using numerical computation, i.e. var(A_1*A_2*A_3*.....*A_n)? Thanks.
Sincerely,
Yanwei Zhang
Department of Actuarial Research and Modeling
Munich Re America
Tel: 609-275-2176
2008 Jul 23
1
Questions on weighted least squares
Hi all,
I met with a problem about the weighted least square regression.
1. I simulated a Normal vector (sim1) with mean 425906 and standard deviation 40000.
2. I simulated a second Normal vector with conditional mean b1*sim1, where b1 is just a number I specified, and variance proportional to sim1. Precisely, the standard deviation is sqrt(sim1)*50.
3. Then I run a WLS regression without the
2008 Sep 05
1
Plot by column
Dear list,
I have the following matrix. How can I make the following plot?
1. The x-axis has index 1:7, and the first column is plotted against index 1, second against 2, and so on.
2. I want the points from the left upper conner including the antidiagonal to be plotted with col=2, and the rest with col=3
[,1] [,2] [,3] [,4] [,5] [,6] [,7]
[1,] 0.589 0.857 0.923 0.944 0.954 0.963
2010 Jul 02
4
Some questions about R's modelling algebra
Hi all,
In preparation for teaching a class next week, I've been reviewing R's
standard modelling algebra. I've used it for a long time and have a
pretty good intuitive feel for how it works, but would like to
understand more of the technical details. The best (online) reference
I've found so far is the section in "An Introduction to R"
2008 Jul 22
2
F test
Dear R users,
I need to do a F test on the hypothesis that a 2 by 1 vector (X_1, X_2)' has the mean vector (M_1, M_2)'. Specifically, I would like to assume the X vector comes from a bivariate Normal distribution (M, Sigma). Then, given 1000 observations on X, I wanted to test if the means of X agree with the means of the target Normal distribution. Any function or package in R could do
2010 Feb 26
1
need help to resolve RODBC error
I've installed R-2.9.2 (64 bit), unixODBC-2.2.14-p2 (64 bit) and RODBC_1.2-5 (64 bit) on a 64 bit Redhat Linux server (Red Hat Enterprise Linux Server release 5.4 (Tikanga), x86_64) release 2.6.18-164.2.1.el5. I've tested the ODBC drive via isql and the test was success:
[yzhang@ROracleTest ~]$ isql -v DRTST yzhang test
+---------------------------------------+
| Connected!
2001 Aug 29
2
Matching Data & Results (Fuzzy-Cluster-Analysis)
Hello,
i use i.e. the cluster-package and the
fanny-object to construct some cluster's and get
the membership'S for every "Person" & Cluster !
My finally problem is to match efficient the data
and the results's togehter in one table!
Until now i use the ODBC-Package and
save both in a access-file and copy them together,
but i can't be sure that the sorting is the
2001 Feb 16
1
command line R; readline history
Hello,
I need help now. I installed R in my Solaris 5.8 box. But two things I am
missing comparing to my old Splus.
1. I used to invoke a command edit Splus by type "Splus -e". So I can surfer
in Splus like ksh environment. Can I do the same in R?
2. I used BSD version of R, which I can use "up" key to call back last
command. But in Sun, I can't make it happened. I
2013 Jan 17
2
error installing KEGGSOAP
Hi, I am new to bioconductor, trying to install KEGGSOAP package, but got warnings() when installing and error message when trying to load the package, can anyone suggest what went wrong?
many thanks
John
> source("http://bioconductor.org/biocLite.R")
Bioconductor version 2.11 (BiocInstaller 1.8.3), ?biocLite for help
> biocLite("KEGGSOAP")
BioC_mirror:
2010 Dec 20
1
source file for rnorm
Dear Sir/Madam:
I am sorry if this is a simple question. I have downloaded the source code for R but could not find the source file that has the rnorm function definition. Could you please let me know which file has the function? Also, in general, how do I find the source file of a given function?
Thanks.
Yue Zhang, CFA
Cohen & Steers Capital Management, Inc.
280 Park Ave., 10th Floor
New
2010 Aug 25
1
why was XENMEM_translate_gpfn_list removed
Why was XENMEM_translate_gpfn_list removed in Xen 4.0. How to achieve
similar purpose in HVM?
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel
2020 Feb 27
2
[PATCH] Update the 5 year logo to 10 year logo
Already outdated, but rounded ;)
I literally just opened the 5yrs logo, changed the text and then done:
inkscape -z -o logo/fish-10yrs.{png,svg}
cp {logo,website}/fish-10yrs.svg
and then updated the rest of the files.
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
---
Makefile.am | 2 +
logo/fish-10yrs.png | Bin 0 -> 65790 bytes
logo/fish-10yrs.svg |
2005 Sep 15
0
Does Theora support scalable decoding?
Hi, every one,
I am a newbie to Theora, it look like very nice. Thank the developers
for the excellent project.
I have a question:
Does Theora support scalable decoding? If not yet, when will it support?
Is there a roadmap for it?
Thanks a lot.