Displaying 20 results from an estimated 2000 matches similar to: "repeatable segfault"
2011 Aug 03
1
NAMESPACE problems
Hi.
I am having difficulty following section 1.6.6 of the R-extensions manual.
I am trying to update the Brobdingnag package to include a NAMESPACE file (the
untb package requires the Brobdingnag package).
Without the NAMESPACE file, the package passes R CMD check cleanly.
However, if I include a NAMESPACE file, even an empty one, R CMD check
gives the following error in 00install.out:
2012 Feb 10
1
stepwise variable selection with multiple dependent variables
Good Day,
I fit a multivariate linear regression model with 3 dependent variables and several predictors using the lm function. I would like to use stepwise variable selection to produce a set of candidate models. However, when I pass the fitted lm object to step() I get the following error:
Error from R:
Error in drop1.mlm(fit, scope$drop, scale = scale, trace = trace, k = k, :
no
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
2007 Nov 23
1
MacOSX 10.4.11 update breaks tests/lapack.R (R 2.6.0)? (PR#10454)
Hello,
It seems the recent Mac OS X 10.4.11 update installed a new
libBLAS.dylib in the Accelerate framework which either contains a bug
itself or exposes a bug somewhere in R's lapack code on the PowerPC G4
and G5.
My build of R 2.6.0 executed the tests/lapack.R code succesfully when
I upgraded when 2.6.0 was released. After the OS update, it now
crashes. This happens both with the version I
2012 Oct 03
1
distinguishing input objects for a function
platform x86_64-apple-darwin9.8.0
arch x86_64
os darwin9.8.0
system x86_64, darwin9.8.0
version.string R version 2.13.1 (2011-07-08)
I am trying to write a function that takes a few objects as input.
test <- function(directory, num = 1:100) {
> }
the argument, "num", has the default value. But when the function is
called, it can take an array
2010 Mar 27
1
R runs in a usual way, but simulations are not performed
Dear addresses, I need perform a batch of 10 000 simulations for each of
4 options considered. (The idea is to obtain the parameter estimates in
a heteroskedastic linear regression model - with additive or mixed
heteroskedasticity - via the Kenward-Roger small-sample adjusted
covariance matrix of disturbances). For this purpose I wrote an R
program which would capture all possible options (true
2006 Nov 21
1
crossprod(x) vs crossprod(x,x)
I found out the other day that crossprod() will take a single matrix
argument;
crossprod(x) notionally returns crossprod(x,x).
The two forms do not return identical matrices:
x <- matrix(rnorm(3000000),ncol=3)
M1 <- crossprod(x)
M2 <- crossprod(x,x)
R> max(abs(M1-M2))
[1] 1.932494e-08
But what really surprised me is that crossprod(x) is slower than
crossprod(x,x):
R>
2005 Jan 27
3
the incredible lightness of crossprod
The following is at least as much out of intellectual curiosity
as for practical reasons.
On reviewing some code written by novices to R, I came
across:
crossprod(x, y)[1,1]
I thought, "That isn't a very S way of saying that, I wonder
what the penalty is for using 'crossprod'." To my surprise the
penalty was substantially negative. Handily the client had S-PLUS
as
2004 Oct 06
3
crossprod vs %*% timing
Hi
the manpage says that crossprod(x,y) is formally equivalent to, but
faster than, the call 't(x) %*% y'.
I have a vector 'a' and a matrix 'A', and need to evaluate 't(a) %*% A
%*% a' many many times, and performance is becoming crucial. With
f1 <- function(a,X){ ignore <- t(a) %*% X %*% a }
f2 <- function(a,X){ ignore <-
2011 Sep 01
4
readBin fails to read large files
Posting for a friend
Begin forwarded message:
From: "Geier, Florian" <florian.geier08@imperial.ac.uk<mailto:florian.geier08@imperial.ac.uk>>
Subject: Fwd: readBin fails to read large files
Date: September 1, 2011 4:10:53 PM GMT+01:00
To:
Begin forwarded message:
Date: 1 September 2011 16:01:45 GMT+01:00
Subject: readBin fails to read large files
Dear all,
I am trying
2003 Oct 17
2
Problems with crossprod
Dear R-users,
I found a strange problem
working with products of two matrices, say:
a <- A[i, ] ; crossprod(a)
where i is a set of integers selecting rows. When i is empty
the result is in a sense random.
After some trials the right answer
(a matrix of zeros) appears.
--------------- Illustration --------------------
R : Copyright 2003, The R Development Core Team
Version 1.8.0
2005 Oct 05
2
eliminate t() and %*% using crossprod() and solve(A,b)
Hi
I have a square matrix Ainv of size N-by-N where N ~ 1000
I have a rectangular matrix H of size N by n where n ~ 4.
I have a vector d of length N.
I need X = solve(t(H) %*% Ainv %*% H) %*% t(H) %*% Ainv %*% d
and
H %*% X.
It is possible to rewrite X in the recommended crossprod way:
X <- solve(quad.form(Ainv, H), crossprod(crossprod(Ainv, H), d))
where quad.form() is a little
2003 Sep 07
3
bug in crossprod? (PR#4092)
# Your mailer is set to "none" (default on Windows),
# hence we cannot send the bug report directly from R.
# Please copy the bug report (after finishing it) to
# your favorite email program and send it to
#
# r-bugs@r-project.org
#
######################################################
# The last line of following code produces a segmentation fault:
x <- 1:10
f <- gl(5,2)
2004 Feb 16
4
Matrix mulitplication
ABCD are four matrix.
A * Inverse((Transpose(A)*Tranpose(B)*B*A+C)) * Transpose(A) * Transpose(B) * D
how to write in R in an efficient way?
---------------------------------
[[alternative HTML version deleted]]
2002 Mar 15
1
Thought on crossprod
Hi everyone,
I do a lot of work with large variance matrices, and I like to use
"crossprod" for speed and to keep everything symmetric, i.e. I often
compute "crossprod(Q %*% t(A))" for "A %*% Sigma %*% t(A)", where
"Sigma" decomposes as "t(Q) %*% Q". I notice in the code that
"crossprod", current definition
> crossprod
function (x,
2008 May 01
4
efficient code - yet another question
Dear list members;
The code given below corresponds to the PCA-NIPALS (principal
component analysis) algorithm adapted from the nipals function in the
package chemometrics. The reason for using NIPALS instead of SVD is
the ability of this algorithm to handle missing values, but that's a
different story. I've been trying to find a way to improve (if
possible) the efficiency of the code,
2008 Mar 10
1
crossprod is slower than t(AA)%*BB
Dear Rdevelopers
The background for this email is that I was helping a PhD student to
improve the speed of her R code. I suggested to replace calls like
t(AA)%*% BB by crossprod(AA,BB) since I expected this to be faster. The
surprising result to me was that this change actually made her code
slower.
> ## Examples :
>
> AA <- matrix(rnorm(3000*1000),3000,1000)
> BB <-
2010 May 08
1
matrix cross product in R different from cross product in Matlab
Hi all,
I have been searching all sorts of documentation, reference cards, cheat
sheets but can't find why R's
crossprod(A, B) which is identical to A%*%B
does not produce the same as Matlabs
cross(A, B)
Supposedly both calculate the cross product, and say so, or where do I
go wrong?
R is only doing sums in the crossprod however, as indicated by
(z <- crossprod(1:4)) # = sum(1 +
2011 Jul 31
4
Error in plotmath
Under
platform x86_64-pc-linux-gnu
arch x86_64
os linux-gnu
system x86_64, linux-gnu
status
major 2
minor 13.1
year 2011
month 07
2009 Jul 07
3
Error due to non-conformable arrays
Hello,
Consider this function for generalized ridge regression:
gre <- function (X,y,D){
n <- dim(X)[1]
p <- dim(X)[2]
intercept <- rep(1, n)
X <- cbind(intercept, X)
X2D <- crossprod(X,X)+ D
Xy <- crossprod(X,y)
bth <- qr.solve(X2D, Xy)
}
# suppose X is an (nxp) design matrix and y is an (nx1) response vector
p <- dim(x)[2]
D<- diag(rep(1.5,p))
bt