Displaying 20 results from an estimated 1000 matches similar to: "Accuracy problem in dchisq for non-central chi-squared"
2006 Feb 03
5
pbinom with size argument 0 (PR#8560)
Full_Name: Uffe H?gsbro Thygesen
Version: 2.2.0
OS: linux
Submission from: (NULL) (130.226.135.250)
Hello all.
pbinom(q=0,size=0,prob=0.5)
returns the value NaN. I had expected the result 1. In fact any value for q
seems to give an NaN. Note that
dbinom(x=0,size=0,prob=0.5)
returns the value 1.
Cheers,
Uffe
2001 Oct 10
4
Weird feature when creating function lists with apply
Hi R-fellows,
can anyone explain this weird feature? I am trying to create a list of
functions with apply, and it appears that there is something strange going
on when the function evaluates the argument a. When I duplicate a into a
local variable b, the result changes !?!
Any pointers? Thank in advance. Cheers,
Uffe
# Create a function which returns a function
> f1 <- function(a)
2003 Apr 13
2
Peculiarity in non-central qchisq for ncp > 294.92 ...
Hello all,
Here's my query:
Running R 1.6.2 on FreeBSD 5.0, and on WinXP, and I find that the
following hangs the process:
dchisq(alpha=0.01, df=1, ncp=295)
but it does work for ncp < 294.92.
Is this general?
Best wishes to all,
Andrew
Andrew Robinson Ph: 208 885 7115
Department of Forest Resources Fa: 208 885 6226
University of Idaho E : andrewr at uidaho.edu
PO
2009 Jan 17
4
Where to find the source codes for the internal function in stats package
Dear all,
I want to see the source codes for "dchisq(x, df, ncp=0, log = FALSE)",
but cannot find it.
I input "dchisq" in the R interface, and then enter, the following message
return:
> dchisq
/*****************************************************/
function (x, df, ncp = 0, log = FALSE)
{
if (missing(ncp))
.Internal(dchisq(x, df, log))
else
2010 Aug 17
2
plotting functions of chi square
Hi! This is going to be a real newbie question, but I can't figure it out.
I'm trying to plot densities of various functions of chi-square. A simple
chi-square plot I can do with dchisq(). But e.g. chi.sq/degrees of freedom I
only know how to do using density(rchisq()/df). For example:
plot(1, type="n", xlab="", ylab="", xlim=c(0,2), ylim=c(0,7))
for (i
2005 Dec 29
1
use of tapply?
I'm still learning how to program with R and I was hoping someone could
take the time to show me how I can rewrite this code?
Many thanks
Tom
data.intersects<-data.frame(
x=c(0.230,0.411,0.477,0.241,0.552,0.230),
y=c(0.119,0.515,0.261,0.431,0.304,0.389),
angle=vector(length=6),
length=vector(length=6),
2007 Oct 24
1
vectorized mle / optim
Hi the list,
I would need some advice on something that looks like a FAQ: the
possibility of providing vectors to optim() function.
Here is a stupid and short example summarizing the problem:
-------------------------------- example 1 ------------ 8<
----------------------
library(stats4)
data <- rnorm(100,0,1)
lik1 <- function(m, v, data) {
N <- length(data)
lik.mean <-
2013 Mar 05
1
Remote database & local database, and adding new weight found vtable error
Hello, guys.
Q1.
now I have load all the docid and its document data into a dictionary for
faster loading data instead of calling
Xapian::MSetIterator i;
i.get_document().get_data();
but I was happened to discover that the dictionaries got by such two method
were different:
both methods use DB1, DB2
method 1:
Xapian::Database db = Xapian::Database(the path of DB1);
Xapian::Database db2 =
2008 Nov 07
4
chi square table
Hi,
How do we get the value of a chi square as we usually look up on the
table on our text book?
i.e. Chi-square(0.01, df=8), the text book table gives 20.090
> dchisq(0.01, df=8)
[1] 1.036471e-08
> pchisq(0.01, df=8)
[1] 2.593772e-11
> qchisq(0.01, df=8)
[1] 1.646497
>
nono of them give me 20.090
Thanks,
cruz
2008 Jan 09
3
likelihood from test result
Is there any automatic mechanism for extracting a likelihood or test
statistic distribution (PDF or CDF) from an object of class "htest" or
from another object of a general class encoding a hypothesis test
result?
I would like to have a function that takes "x", an object of class
"htest", as its only argument and that returns the likelihood or test
statistic
2013 Jun 18
2
offset en bucle
Amigos de la erre.
He creado mi primer bucle con for para entrenar unos modelos con GAM. La
respuesta es quasipoisson porque estoy trabajando con densidades de peces.
Sin embargo, tengo un problema, no se muy bien como aƱadir el offset a la
formula siguiente cuando creo el bucle.
GAM.A1 <-gam ((DYO)~s(DMA,k=4)+ s(WOD,k=4)+s(CIN,k=4)+s(DRA,k=4)+s(DBR,k=4)
2008 Aug 21
2
Help Regarding 'integrate'
I have an R function defined as:
f<-function(x){
return(dchisq(x,9,77)*((13.5/x)^5)*exp(-13.5/x))
}
Numerically integrating this function, I observed a couple of things:
A) Integrating the function f over the entire positive real line gives an
error:
> integrate(f,0,Inf)
Error in integrate(f, 0, Inf) : the integral is probably divergent
B) Increasing the interval of integration
2008 Aug 21
1
pnmath compilation failure; dylib issue?
(1) ...need to speed up a monte-carlo sampling...any suggestions about
how I can get R to use all 8 cores of a mac pro would be most useful
and very appreciated...
(2) spent the last few hours trying to get pnmath to compile under os-
x 10.5.4...
using gcc version 4.2.1 (Apple Inc. build 5553) as downloaded from
CRAN, xcode 3.0...
...xcode 3.1 installed over top of above after
2002 Dec 30
1
Java Swing App
I'm rather new to Wine, and I'm trying to run a Java Swing application.
I'm having trouble with it. Has anyone else gotten Swing-based apps to
run?
I have a test case, basically a swing "hello world" app, and I haven't
been able to get it to work either. Here's what happens when I try to
compile it:
[dritch@twitch wine]$ wine -- c:/jdk1.3/bin/javac -g -d
2010 Nov 30
1
rcauchy density distribution
Hello, I'm taking samples from certain distributions and drawing a density
distribution over the histogram of the samples
It works fine for the chi-square and for the normal, but not for the cauchy. Any
idea what I'm doing wrong? Thanks
x <- rchisq(10000, df = 4)
hist(x, freq = FALSE, breaks=100)
curve(dchisq(x, df = 4), col = 2, add = TRUE)
x <- rnorm(10000)
hist(x, freq =
2009 May 21
1
Need help on ploting Histograms
this is the command i made for a normal distribution, but when i try to plot
the histograms, i dont know why the bars don't stick on the line...
nsamples<-1000
sampsize<-15
Samples<-matrix(rnorm(nsamples*sampsize,0,1),nrow=nsamples)
a<-apply(Samples,1,var)
NC14<-a*14
x<-0:40
plot(x,dchisq(x,14),type='h')
hist(NC14,freq=F,add=T)
--
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2008 Jul 16
4
Likelihood ratio test between glm and glmer fits
Dear list,
I am fitting a logistic multi-level regression model and need to test the difference between the ordinary logistic regression from a glm() fit and the mixed effects fit from glmer(), basically I want to do a likelihood ratio test between the two fits.
The data are like this:
My outcome is a (1,0) for health status, I have several (1,0) dummy variables RURAL, SMOKE, DRINK, EMPLOYED,
2005 Jan 21
2
chi-Squared distribution in Friedman test
Dear R helpers:
Thanks for the previous reply. I am using Friedman racing test. According the the book "Pratical Nonprametric Statistic" by WJ Conover, after computing the statistics, he suggested to use chi-squared or F distribution to accept or reject null hypothesis. After looking into the source code, I found that R uses chi-sqaured distribution as below:
PVAL <-
2003 Sep 03
3
plotting a distribution curves
Hi,
is there a way to plot distribution curves (say normal or chi sq etc)
from within R?
For example I looked up the *chisq family of functions but I'm not sure
as to how I would use them to generate a plot of the chi sq distribution
(for arbitrary d.o.f).
Thanks,
-------------------------------------------------------------------
Rajarshi Guha <rajarshi at presidency.com>
2005 Dec 13
8
superimpose density line over hist
Hi all,
I'm trying to superimpose a rchisq density line over a histogram with
something like:
hist(alnlength)
lines(density(rchisq(length(alnlength), 4)),col="red")
But the rchisq line won't appear anywhere,
Anyone knows what I am missing here?
Thanks in advance,
Albert.