Displaying 20 results from an estimated 1000 matches similar to: "power law distribution; making new distributions"
2002 Jan 09
3
R package-building
Hello,
I am building a package to read in a pretty common atmospheric data format
and create a SKEW-T, log p diagram (also very common for the atmospheric
community).
The problem is this: How should one address the (ASCII) data files so that
the examples find them? I have read through the "Writing R Extensions"
document and still have a problem.
There seems to be some sort of
2003 Sep 17
3
[Bug 665] sshd doesn't work on Mac OS X
http://bugzilla.mindrot.org/show_bug.cgi?id=665
Summary: sshd doesn't work on Mac OS X
Product: Portable OpenSSH
Version: 3.7p1
Platform: PPC
OS/Version: Mac OS X
Status: NEW
Severity: normal
Priority: P2
Component: sshd
AssignedTo: openssh-bugs at mindrot.org
ReportedBy: max at
2004 Aug 04
2
fitting distributions
Hello,
I also try to fit a skewed distribution (like skewed student t) to data
points. Do you have an idee howto do this???
thank you
fabrice dusonchet
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2004 Mar 19
3
Incomplete Gamma Functions and GammaDistribution Doc errata.
Hello all,
In the course of trying to implement the CDF of an
InverseGammaDistribution, I have run across the need for an igamma()
function. Several others have needed this function but the answers I
have found so far are not totally clear to me. I'm writing for three
reasons:
1) to present a small error in the docs
2) to clarify the approach we are expected to take
3) to request,for the
2005 Aug 12
3
General expression of a unitary matrix
Hi, all,
Does anybody got the most general expression of a unitary matrix?
I found one in the book, four entries of the matrix are:
(cos\theta) exp(j\alpha); -(sin\theta)exp(j(\alpha-\Omega));
(sin\theta)exp(j(\beta+\Omega)); (cos\theta) exp(j\beta);
where "j" is for complex.
However, since for any two unitary matrices, their product should also
be a unitary matrix. When I
2006 Jun 26
2
Inverse Error Function
Do any of the R libraries have an implementation of the Inverse Error
Function (Inverse ERF)?
ref:
http://mathworld.wolfram.com/InverseErf.html
http://functions.wolfram.com/GammaBetaErf/InverseErf/
Thanks,
Nathan
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2010 Jan 05
4
solving cubic/quartic equations non-iteratively
To R-helpers,
R offers the polyroot function for solving mentioned equations
iteratively.
However, Dr Math and Mathworld (and other places) show in detail how to
solve mentioned equations non-iteratively.
Do implementations for R that are non-iterative and that solve mentioned
equations exists?
Regards, Mads Jeppe
2006 Jun 15
2
Standard Deviation Distribution
I'm having trouble with the standard deviation distribution
as shown on http://mathworld.wolfram.com/StandardDeviationDistribution.html .
(Eric Weisstein references Kenney and Keeping 1951, which I can't check.)
I believe the graphs they show, but when I code the function in R, according to the listed formula,
I get very different graphs.
Would someone please point out my error or tell
2010 Jan 19
2
Copyright versus Licenses
My company recently started using a R library from RCRAN that is
licensed under the LGPL Version 2 or greater per the DESCRIPTION file,
but contains no copy of the LGPL notice, or any copyright notice. I've
grown accustomed to paying attention to copyright and licensing as a
Debian package maintainer, and sent the author of the package an email
expressing my concern. The author believed that
2011 Nov 01
2
drawing ellipses in R
Hello,
I have been following the thread dated Monday, October 9, 2006 when Kamila Naxerova asked a question about plotting elliptical shapes. Can you explain the equations for X and Y. I believe they used the parametric form of x and y (x=r cos(theta), y=r sin(theta). I don't know what r is here ? Can you explain 1)the origin of these equations and 2) what is r?
Sincerely,
Mary A. Marion
2011 Apr 28
5
fisher exact for > 2x2 table
I'm using fisher.exact on a 4x2 table and it seems to work.
Does anyone know exactly what is going on? I thought fisher.exact is only
for 2x2 tables.
Note: I can't use chi-squared because I have a couple of cells with 0 and <
5 observations.
--
View this message in context: http://r.789695.n4.nabble.com/fisher-exact-for-2x2-table-tp3481979p3481979.html
Sent from the R help
2005 Aug 23
1
GLM->Repeated measures (multivariate)
Dear subscribers,
I'm trying to make the switch from M$ Windows to Linux (KDE) and found the
R-cran project for statistical analysis. I'm not a genius in statistics so
the command line interface is a bit hard for me.
I need an analogue way to do the SPSS General Linear Model->Repeated
Measures (multivariate) but I don't have a clue how to perform this in
R-cran. Can maybe
2004 Jun 16
2
erf function documentation
Hi all. I may be wrong, (and often am), but in trying
to determine how to calculate the erf function, the
documentation for 'pnorm' states:
## if you want the so-called 'error function'
erf <- function(x) 2 * pnorm(x * sqrt(2)) - 1
## and the so-called 'complementary error function'
erfc <- function(x) 2 * pnorm(x * sqrt(2),
lower=FALSE)
Should, instead, it read:
2010 Jan 15
1
Using multicore with an open pdf device results in corrupt pdf (PR#14186)
The attached code produces corrupted pdfs (test2.pdf, test4.pdf and
test5.pdf). The resulting pdf depends on how many cores are available on
the machine.
I don't see why there should be any difference between the pdfs (exept for
the timestamp). Doing many operations involving mclapply can increase the
size of the resulting pdf by ten times!
Thank you for checking this.
require(multicore)
2011 Feb 11
2
fitdistr question
Hello,
I tried to fit a poisson distribution but looking at the function
fitdistr() it does not optimize lambda but simply estimates the mean
of the data and returns it as lambda. I'm a bit confused because I was
expecting an optimization of this parameter to gain a good fit...
If I would use mle() of stats4 package or mle2() of bbmle package, I
would have to write the function by myself
2002 Dec 11
3
Modified Bessel Function - 2nd kind
In order to fit a probability distribution proposed by Sichel [Journal of
the Royal Statistical Society. Series A (General), Vol. 137,
No. 1. (1974), pp. 25-34], I need a modified Bessel function of the 2nd
kind. I notice that the base package of "R" only has modified Bessel
functions of the 1st and 3rd kind. Does a modified Bessel function of the
2nd kind exist anywhere?
Many
2004 Jan 30
2
request for comments --- package "distr" --- S4 Classes for Distributions
Hello,
after some discussions with Martin Maechler and Josef Leydold (WU Wien),
we have felt the need for some package that should allow for an
object-orientated
approach to distributions.
Our small group at Bayreuth now has developed a package "distr" which
tries to fill this gap, implementing distributions by means of
S4--classes.
A mother class "Distribution" is
2007 Jun 11
1
Gini coefficient in R
If I use the Ineq library and the Gini function in this way:
>Gini(c(100,0,0,0))
I obtain the result 0.75 instead of 1 (that is the perfect inequality).
I think Gini's formula in Ineq is based on a formula as reported here:
http://mathworld.wolfram.com/GiniCoefficient.html
but in the case of perfect inequality:
x_1=.......=x_n-1 =0
x_n>0
these formula are equal to 1 - 1/n, not to
2005 Jun 23
2
solving equation system
Hello,
I want to solve some two dimensional equation system with R. Some systems
are not solvable analytically.
Here is an example:
(I) 1/n*sum{from_i=1_to_n}(Xi) = ln lambda + digamma(c)
(II) mean(X) = x / lambda
I want to find lambda and c,
which R-function could do that task?
Carsten
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2008 Oct 09
4
runs of heads when flipping a coin
Can someone recommend a method to answer the following type of question:
Suppose I have a coin with a probability hhh of coming up heads (and 1-hhh
of coming up tails)
I plan on flipping the coin nnn times (for example, nnn = 500)
What is the expected probability or frequency of a run of rrr heads* during
the nnn=500 coin flips?
Moreover, I would probably (excuse the pun) want the answer for a