Displaying 7 results from an estimated 7 matches for "evec".
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2010 Nov 10
2
prcomp function
...ing easy example:
first I define a matrix A
>A<-matrix(c(0,1,4,1,0,3,4,3,0),3,3)
then I apply PCA on A
>trans<-prcomp(A,retx=T,center=F,scale.=F,tol=NULL)
>eval<-trans$sdev*trans$sdev #eval is the vector of the eigenvalues of
cov(A) (according to the cited help text above)
>evec<-trans$rotation #evec is the matrix with the eigenvectors of cov(A) as
columns (according to the cited help text above)
now the eigenvalue equation should be valid, i.e. it should hold
cov(A)%*%ev[,1]=ew[1]*ev[,1]. But it doesn?t, my result:
cov(A)%*%ev[,1]= t(-0.8244927, -0.8325664,0.8244927)...
2003 Mar 26
1
Solving equations
Hello,
Does somebody knows if there exists a function which solves a set of
equation, say f(vars),
for the variables vars (similar to Solve in mathematica).
The functions I am considering are of the form f(t) ~ A*exp(B*t), where
A and B are matrices.
Thanks Thomas
2010 Jan 11
3
Eigenvectors and values in R and SAS
Hi,
I was wondering if function eigen() does something different from the
function call eigen() in SAS.
I'm in the process of translating a SAS code into a R code and the values of
the eigenvectors and eigenvalues of a square matrix came out to be different
from the values in SAS.
I would also appreciate it if someone can explain the difference in simple
terms. I'm pretty new to both
2010 Sep 29
1
Fitting a half-ellipse curve
Dear mailing list,
I have following array:
X2 Y2
[1,] 422.7900 6.0
[2,] 469.8007 10.5
[3,] 483.9428 11.0
[4,] 532.4917 25.5
[5,] 596.1942 33.5
[6,] 630.8496 40.5
[7,] 733.2996 45.0
[8,] 946.4779 32.0
[9,] 996.8068 35.5
[10,] 1074.3310 23.0
I do afterwards the following:
plot.new()
plot.window(xlim=c(min(X1)-50,max(X1)+50),
2005 Dec 04
1
Understanding nonlinear optimization and Rosenbrock's banana valley function?
...l; i=", i,
"; p=", round(p, 3), "; dp=", signif(dp, 2),
"; eig(hessian)=",signif(d2f.eig$values, 4))
v.max <- (1+max(abs(d2f.eig$values)))
v.adj <- pmax(.001*v.max, abs(d2f.eig$values))
evec.df <- (t(d2f.eig$vectors) %*% df)
dp <- (-(d2f.eig$vectors %*%
(evec.df/(1+v.adj))))
}
else{
cat(".")
dp <- dp/2
}
}
f.i <- f(p+dp)
f2 <- f(p+dp/2)...
2002 Nov 26
3
dovecot and pop3
Dear dovecotters:
I'm becoming interested in dovecot as a replacement for UW-IMAPD. Any
project that claims it's the "postfix of ____ servers" deserves a looksee.
If indeed I were to going to switch at some point, I'd need to replace
the UW POP3 server (which is a part of the UW package). I would prefer
one that actually used the dovecot IMAP server instead of going to
2023 Mar 11
3
Multiple Assignment built into the R Interpreter?
Dear R Core,
working on my dynamic factor modelling package, which requires several
subroutines to create and update several system matrices, I come back to
the issue of being annoyed by R not supporting multiple assignment out of
the box like Matlab, Python and julia. e.g. something like
A, C, Q, R = init_matrices(X, Y, Z)
would be a great addition to the language. I know there are several