Displaying 20 results from an estimated 2000 matches similar to: "How to see a R function's code"
2003 Jul 16
2
Density function for non-central t distribution
Hi,
I've written some C code for density evaluation of the non-central t distribution. It works
with the R-1.7.1 source code if placed in the src/nmath directory and after appropriate
changes are made to Makefiles, to the dt function in src/library/base/R/distn.R etc.
I haven't read a lot of R source code so it may need some R-ification, but I've tried to use the
dt.c file as a
2007 Mar 21
3
question on suppressing error messages with Rmath library
Dear list,
I have been using the Rmath library for quite a while: in the current instance, I am calling dnt (non-central t density function) repeatedly for several million. When the argument is small, I get the warning message:
full precision was not achieved in 'pnt'
which is nothing unexpected. (The density calls pnt, if you look at the function dnt.) However, to have this happen a
2006 Dec 19
3
Bug in rt() ? (PR#9422)
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
<<insert bug report here>>
Reproduced on Debian and Windows ...
On 2.4.x if you execute
set.seed(12345)
t.1 <- rt(n = 1000, df = 20)
set.seed(12345)
t.2 <- rt(n = 1000, df = 20, ncp = 0)
all.equal(t.1, t.2) ## Not close to true
This appears to be due to the fact that in 2.4.x rt is now
rt
function (n, df, ncp = 0)
{
if
2008 Jun 14
1
qt with ncp>37.62
help(qt) states that:
"ncp non-centrality parameter delta; currently except for rt(), only for
abs(ncp) <= 37.62"
so I would expect that calling qt with non-centrality parameter exceeding
37.62 should fail, instead e.g. calling
> mapply(function(x) qt(p = 0.9, df = 55, ncp = x),35:45)
gives:
[1] 40.21448 41.35293 42.49164 43.68862 44.82945 45.97048 47.11170 48.25310
[9]
2007 Jan 31
2
Bug in 'pchisq' for x=0.0 (PR#9485)
The function 'pchisq' from the 'stats' library gives a wrong result if the
argument equals exactly zero:
# Upper tail of central 1-df chi^2 distribution
> pchisq(1 , 1, ncp=0, lower.tail = F, log.p = FALSE)
[1] 0.3173105
> pchisq(0.5 , 1, ncp=0, lower.tail = F, log.p = FALSE)
[1] 0.4795001
> pchisq(0.01 , 1, ncp=0, lower.tail = F, log.p = FALSE)
[1]
2009 May 04
3
problem with ms office
Friends,
I installed MS office 2k7 with wine 1.1.15. I am able to open the
applications and work on it. However if i try to copy a figure from
powerpoint and paste is on the word, it is not working. The reverse is also
not working.
In addition, i am not able to move the figures in the work file to the
appropriate positions. I dnt understand what is going wrong. Any suggestion
on how to resolve
2006 Dec 10
1
Noncentral t & F distributions
Dear List:
The square of the noncentral t-statistic with noncentrality parameter
\delta is a noncentral F with noncentrality parameter \lambda=\delta^2.
So, t^2_{\nu,\delta} = F_{1,\nu,\lambda=\delta^2}. Consequently, it
should follow that t^2_{1-\alpha/2,\nu,\delta} =
f_{1-alpha,1,\vu,\lambda=\delta^2}. However, this is not what is
happening with the following code. The central
2002 Oct 17
3
Non-central distributions
Hi Folks,
I note that, while the "chisq" functions
dchisq(x, df, ncp=0, log = FALSE)
pchisq(q, df, ncp=0, lower.tail = TRUE, log.p = FALSE)
qchisq(p, df, ncp=0, lower.tail = TRUE, log.p = FALSE)
rchisq(n, df, ncp=0)
all have a slot for the non-centrality parameter "ncp", of
the functions for the t and F distributions:
dt(x, df, log = FALSE)
2000 Nov 28
1
non-centrality parameter in pf() (PR#752)
Bug Description:
Problem with the function pf() when the non-centrality
parameter is large. Here is a sample command. You should
see a smooth line from 0 to about 55, and then the values
of pf() go crazy from 55 to 100.
############################
ncp <- seq(0,100,length=200)
plot(ncp,pf(5,7,2,ncp=ncp))
############################
Version:
platform = i686-pc-linux-gnu
arch = i686
os =
2007 Oct 12
2
Dock-N-Talk with Asterisk, Anyone?
Hello My Aster-Friends!
I would like to hear if anyone out there in
Asteriskland has used the Dock-N-Talk (DNT) box to
connect cell phones to Asterisk box.
I have a couple of these boxes that I need to make
work with Asterisk, connected with Digium TDM400P
card. Anyone tried it before, and how did it go?
Thank you.
Jeng
___________________________________________________________
Yahoo!
2008 Jan 07
2
chi-squared with zero df (PR#10551)
Full_Name: Jerry W. Lewis
Version: 2.6.1
OS: Windows XP Professional
Submission from: (NULL) (24.147.191.250)
pchisq(0,0,ncp=lambda) returns 0 instead of exp(-lambda/2)
pchisq(x,0,ncp=lambda) returns NaN instead of exp(-lambda/2)*(1 +
SUM_{r=0}^infty ((lambda/2)^r / r!) pchisq(x, df + 2r))
qchisq(.7,0,ncp=1) returns 1.712252 instead of 0.701297103
qchisq(exp(-1/2),0,ncp=1) returns 1.238938
2006 Jul 01
1
noncentral F-distributed random numbers (PR#9055)
Full_Name: Long Qu
Version: 2.3.1
OS: Windows XP
Submission from: (NULL) (64.113.93.235)
The QQ-plot of two versions of simulating noncentral F-distributed random
numbers has quite different scales:
> qqplot(rf(1000,2,15,3),qf(runif(1000),2,15,3))
The rf() function reads:
> rf
function (n, df1, df2, ncp = 0)
{
if (ncp == 0)
.Internal(rf(n, df1, df2))
else rchisq(n, df1,
2004 Sep 06
1
qchisq (PR#7212)
Full_Name: David Clayton
Version: 1.8.1
OS: Linux
Submission from: (NULL) (131.111.126.242)
qchisq behaves very strangely when ncp is passed as zero (forcing internal
qnchisq to be called) when first argument is small.
Eg
> qchisq(1-1e-6, 1, ncp=0, lower.tail=TRUE)
qchisq(1-1e-6, 1, ncp=0, lower.tail=TRUE)
[1] 1024
while, if ncp is unspecified,
> qchisq(1-1e-6, 1)
qchisq(1-1e-6, 1)
2007 Nov 08
1
64-bit R-build on Mac OS X 10.4 - make check failures
Hi all,
I compiled 64-bit R on an Apple Mac G5 running OS X, but it failed
make check. Simon Urbanek suggested I post results to R-devel.
> On Nov 6, 2007, at 10:23 PM, Steven McKinney wrote:
>
> > Hi Simon,
> >
> > Would you be able to give more guidance on how to compile 64-bit
> > libiconv for Tiger,
>
> You can get the sources from Apple and compile
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
2005 Apr 26
1
Finding 'ncp' for t
Hi Folks,
I'm looking for a neat procedure for the following:
Given t0 such that
pt(t0,df,ncp=0) = alpha (given)
find ncp0 such that for given beta
pt(t0,df,ncp=ncp0) = (1 - beta)
(In other words, what's the ncp such that you get power (1-beta)
to detect it, using a 1-sided test with size alpha when ncp = 0?)
In the past I've done the groping by hand, but this time it
needs
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
2004 Jan 19
2
small bug on qchisq (PR#6442)
Full_Name: Drouilhet R?my
Version: 1.8.1
OS: Linux
Submission from: (NULL) (195.221.43.136)
qchisq(1,10) works well but qchisq(1,10,ncp=0) does not work whereas ncp=0 is
the default value of the function qchisq(1,10). (of course, 10 will be replaced
by any integer value).
Let us notice that this bug occurs only when applying probability one.
(qchisq(seq(0,.9,.1),10,ncp=0) works very well).
2001 Nov 29
1
errors in help("TDist")?
Dear all,
The help page on the t distribution says:
The most used applications are power calculations for t-tests:
Let T= (mX - m0) / (S/sqrt(n)) where mX is the `mean' and S the
sample standard deviation (`sd') of X_1,X_2,...,X_n which are
i.i.d. N(mu,sigma^2). Then T is distributed as non-centrally t
with `df'= n-1 degrees of freedom and non-centrality
2001 Dec 04
1
pt fails with ncp
?pt states that ncp=0 is default, so this is correct
> pt(3,3)
[1] 0.9711656
> pt(3,3, ncp=0)
[1] 0.9711656
but this is not
> pt(-Inf,3)
[1] 0
> pt(-Inf,3,ncp=0)
[1] 0.5
is it?
Torsten
--please do not edit the information below--
Version:
platform = i686-pc-linux-gnu
arch = i686
os = linux-gnu
system = i686, linux-gnu
status = Under development (unstable)
major = 1
minor