Displaying 14 results from an estimated 14 matches for "roundoff".

2011 Apr 24

2

random roundoff?

...e0] or nearby, I do:
cerr << "some stuff" << endl;
mat3 = matmult(mat1,mat2);
I get a difference of the order 1.0e-15 depending on whether the
cerr line does or does not end in "endl" as shown.
I am imagining that there is some "randomness" in the roundoff
that depends on the I/O situation. Is this credible? Any other
suggestions?
Thanks for your help,
Mike.

2012 Sep 25

1

how to pass a function to a function inside a function

....tol),
as.double(rel.tol), limit = limit, PACKAGE = "base")
}
res <- wk[c("value", "abs.error", "subdivisions")]
res$message <- switch(wk$ierr + 1, "OK", "maximum number of
subdivisions reached",
"roundoff error was detected", "extremely bad integrand behaviour",
"roundoff error is detected in the extrapolation table",
"the integral is probably divergent", "the input is invalid")
if (wk$ierr == 6 || (wk$ierr > 0 && stop.on.er...

2012 Jan 10

1

Lapack routine dgesv: system is exactly singular

Hi
I have a problem with this error, I have searched the archives and found
previous discussion about this, can I cannot understand how the explanations
apply to what I am trying to do.
I am trying to do Log_rank Survival analysis, I have included tables and str
command, is it a factor/integer problem? If so how do I correct this, as all
my attempt to recode the data have failed.

2007 Jun 29

1

Comparison: glm() vs. bigglm()

Hi,
Until now, I thought that the results of glm() and bigglm() would
coincide. Probably a naive assumption?
Anyways, I've been using bigglm() on some datasets I have available.
One of the sets has >15M observations.
I have 3 continuous predictors (A, B, C) and a binary outcome (Y).
And tried the following:
m1 <- bigglm(Y~A+B+C, family=binomial(), data=dataset1, chunksize=10e6)

2002 Jan 07

0

New package: colSums

...'s not NA or NaN
if x==x), which works really great for me, but may not be portable. If it
doesn''t work for you, try modifying the #define line in colSums.c. I would
like to hear about platforms where this fails.
- colVars is very naive, e.g. I''m probably exacerbating roundoff error when
mu >> sigma. I personally don''t worry because in finance, mu (return) is
never >> sigma (risk) :-). The S-Plus documentation for colVars claims they
do something fancy with the "two-pass method described in Chan, Golub, and
LeVeque (1983)" that I...

2004 Jun 01

0

qhull in R?

...hulls, Delaunay triangulations, halfspace
intersections about a point, Voronoi diagrams, furthest-site Delaunay
triangulations, and furthest-site Voronoi diagrams. It runs in 2-d, 3-d,
4-d, and higher dimensions. It implements the Quickhull algorithm for
computing the convex hull. Qhull handles roundoff errors from floating
point arithmetic. It computes volumes, surface areas, and approximations
to the convex hull."
Thanks
Agus
PLEASE NOTE NEW E-MAIL ADDRESS
Dr. Agustin Lobo
Instituto de Ciencias de la Tierra (CSIC)
Lluis Sole Sabaris s/n
08028 Barcelona SPAIN
tel 34 93409 5410
fax 3...

2010 Jun 02

0

[LLVMdev] Generating Floating point constants

On Jun 2, 2010, at 3:28 AMPDT, Stéphane Letz wrote:
>
> Le 2 juin 2010 à 12:21, Eli Friedman a écrit :
>
>> On Wed, Jun 2, 2010 at 2:59 AM, Stéphane Letz <letz at free.fr> wrote:
>>> Hi,
>>>
>>> We need to generate "Floating point constants" in our code. In http://llvm.org/docs/LangRef.html it is explained that FP has to

2008 Apr 09

2

GLM fitting in R and Statistica

Hi,
I have a problem concerning discrepances between R (which I use) and
Statistica (which uses my supervisor). I can't say what is the origin
of these differences but unfortunately my supervisor doesn't know that
either.
Our response variable is number (or presence/absence) of parasites in
rodents and explanatory variables are presence/absence of several
alleles. The rodents

2010 Jun 02

3

[LLVMdev] Generating Floating point constants

Le 2 juin 2010 à 12:21, Eli Friedman a écrit :
> On Wed, Jun 2, 2010 at 2:59 AM, Stéphane Letz <letz at free.fr> wrote:
>> Hi,
>>
>> We need to generate "Floating point constants" in our code. In http://llvm.org/docs/LangRef.html it is explained that FP has to follow special encoding rules to be handled by LLVM later one (hexadecimal

2008 Mar 31

5

[LLVMdev] Additional Optimization I'm Missing?

Hello, I'm working on using the LLVM JIT for a little project of mine,
amazing work first off! I have a question about optimization passes. I
initially have this function I've created, in python it looks like this:
OS_end = 50OS_start = 0OS_timestep = 1birth_rate = .3population =
30.0for time in range(OS_start, OS_end, OS_timestep):
births = birth_rate * population
deaths = 0.1

2008 Aug 01

5

drop1() seems to give unexpected results compare to anova()

Dear all,
I have been trying to investigate the behaviour of different weights in
weighted regression for a dataset with lots of missing data. As a start
I simulated some data using the following:
library(MASS)
N <- 200
sigma <- matrix(c(1, .5, .5, 1), nrow = 2)
sim.set <- as.data.frame(mvrnorm(N, c(0, 0), sigma))
colnames(sim.set) <- c('x1', 'x2') # x1 & x2 are

2002 Jan 07

3

tool for listening tests

I've been looking around for a tool to compare the quality of different
audio files, didn't find anything, and so botched together something over
the past few days:
http://www.btinternet.com/~jfchapman/files/mcp.zip (Win32, 266Kb)
It's just a small tool for playing up to 3 files simultaneously, with the
ability to switch between the outputs to compare the sound

2001 Mar 21

3

bitrtate peeling and lossless compression

I just read some of the discussion on the list about 'bitrate peeling' and
remembered an interview of Monty that I have read recently. In it he says
that Vorbis uses MCDTs <sp> and that these are theoretically reversable.
And now, I learn that theoretically we can use bitrate peeling to make
smaller files from larger ones, and that leads to my question. Could I
theoretically

2009 Sep 22

5

Indexing Ogg files for faster seeking

I've developed an indexer which embeds a keyframe index track in Ogg
files. It embeds the index in its own track, so that players that don't
understand or don't want to use the index can just ignore it.
Ogg needs this to make seeking over networks faster and more efficient.
Currently we must do a bisection search when seeking, which usually
takes aound 6 HTTP requests, give or