Displaying 20 results from an estimated 40 matches for "bessely".
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bessel
2010 Feb 10
1
looping problem
Hi R-users,
I have this code here:
library(numDeriv)
fprime <- function(z)
{ alp <- 2.0165;
rho <- 0.868;
# simplified expressions
a <- alp-0.5
c1 <- sqrt(pi)/(gamma(alp)*(1-rho)^alp)
c2 <- sqrt(rho)/(1-rho)
t1 <- exp(-z/(1-rho))
t2 <- (z/(2*c2))^a
bes1 <- besselI(z*c2,a)
t1bes1 <- t1*bes1
c1*t1bes1*t2
}
## Newton
2003 Aug 20
2
Method of L-BFGS-B of optim evaluate function outside of box constraints
Hi, R guys:
I'm using L-BFGS-B method of optim for minimization problem. My function
called besselI function which need non-negative parameter and the besselI
will overflow if the parameter is too large. So I set the constraint box
which is reasonable for my problem. But the point outside the box was
test, and I got error. My program and the error follows. This program
depends on CircStats
2007 Jun 18
1
two bessel function bugs for nu<0
...;- -0.4
print(paste(besselI(x, nu, TRUE), "=", exp(-x)*besselI(x, nu, FALSE)))
#fix:
#$ diff bessel_i_old.c bessel_i_new.c
#57c57
#< bessel_k(x, -alpha, expo) * ((ize == 1)? 2. : 2.*exp(-x))/M_PI
#---
#> bessel_k(x, -alpha, expo) * ((ize == 1)? 2. : 2.*exp(-2.0*x))/M_PI
#bug 2: besselY() for nu<0
#don't know how to check in R; a few random checks against mathematica 5.2
#fix:
#$ diff bessel_y_old.c bessel_y_new.c
#55c55
#< return(bessel_y(x, -alpha) + bessel_j(x, -alpha) * sin(-M_PI * alpha));
#---
#> return(bessel_y(x, -alpha) * cos(M_PI * alpha) - bessel_j(x,
-al...
2007 Sep 22
0
error messages
Hi,
I have a density that I need to get MLEs from, which includes definite integrals both in the denominator and in the numerator of the density function. It looks like the outcome depends on the initial values given. My program is shown below:
library(circular)
########################################
4 parameters
########################################
z<-rvonmises(100,0,1)
2010 Jan 26
1
newton method for single nonlinear equation
Hi r-users,
I would like to solve for z values using newton iteration method. I 'm not sure which part of the code is wrong since I'm not very good at programming but would like to learn. There seem to be some output but what I expected is a vector of z values. Thank you so much for any help given.
newton.inputsingle <- function(pars,n)
{ runi <- runif(974, min=0, max=1)
2002 Apr 19
1
FW: Problem compiling on HP-UX 10.20
Here is a copy of the last few lines in base-Ex.Rout.fail:
> x <- seq(3,500);yl <- c(-.3, .2)
> plot(x,x, ylim = yl, ylab="",type='n', main = "Bessel Functions
Y_nu(x)")
> for(nu in nus){xx <- x[x > .6*nu]; lines(xx,besselY(xx,nu=nu), col =
nu+2)}
> legend(300,-.08, leg=paste("nu=",nus), col = nus+2, lwd=1)
>
> x <- seq(10,50000,by=10);yl <- c(-.1, .1)
> plot(x,x, ylim = yl, ylab="",type='n', main = "Bessel Functions
Y_nu(x)")
> for(nu in nus){xx <- x[...
2009 Jun 03
2
code for double sum
Hi R-users,
I wrote a code to evaluate double sum as follows:
ff2 <- function(bb,eta,z,k)
{ r <- length(z)
for (i in 1:r)
{ sm1 <- sum((z[i]*bb/2)*(psigamma((0:k)+eta+1,deriv=0)/(factorial(0:k)*gamma((0:k)+eta+1))))
sm2 <- sum((besselI(z[i]*bb,eta)*log(z[i]*bb/2) - sm1)/besselI(z[i]*bb,eta))
sm2
}
ff2(bb,eta,z,10)
but it gave me the following message:
>
2002 Nov 26
2
Existence of non-vectorised functions
Dear R-Group:
Recently, I ran into a problem. I was using a function called "I.1",
which evaluates the first-order modified Bessel function of the first
kind, in the package "CircStats". This function is not vectorized,
since it uses a couple of "if" conditions. However, when I called this
function with a vector argument, I got no error/warning messages in
2010 Jun 15
1
Error in nlm : non-finite value supplied by 'nlm'
Hello,
I am trying to compute MLE for non-Gaussian AR(1). The error term follows a difference poisson distribution. This distribution has one parameter (vector[2]).
So in total I want to estimate two parameters: the AR(1) paramter (vector[1]) and the distribution parameter.
My function is the negative loglikelihood derived from a mixing operator.
f=function(vector)
2007 Sep 11
1
Fitting Data to a Noncentral Chi-Squared Distribution using MLE
Hi, I have written out the log-likelihood function to fit some data I have (called ONES20) to the non-central chi-squared distribution.
>library(stats4)
>ll<-function(lambda,k){x<-ONES20; 25573*0.5*lambda-25573*log(2)-sum(-x/2)-log((x/lambda)^(0.25*k-0.5))-log(besselI(sqrt(lambda*x),0.5*k-1,expon.scaled=FALSE))}
> est<-mle(minuslog=ll,start=list(lambda=0.05,k=0.006))
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 May 05
4
Discontinuities in a simple graph (machine precision?)
Hi,
I've got an ugly but fairly simple function:
mdevstdev <- function(a){
l <- dnorm(a)/(1-pnorm(a))
integrand <- function(z)(abs(z-l)*dnorm(z))
inted <- integrate(integrand, a, Inf)
inted[[1]]/((1- pnorm(a))*sqrt((1 + a*l - l^2)))
}
I wanted to quickly produce a graph of this over the range [-3,3] so I
used:
plotit <-function(x=seq(-3,3,0.01),...){
2009 Mar 23
4
newton method
Hi R-users,
Does R has a topic on newton's method?
Thank you for the info.
2010 Jan 26
1
Newton method
Hi r-users,
I hope somebody can help me with this code.
I would like to solve for z values using newton iteration method. I 'm not sure which part of the code is wrong since I'm not very good at programming but would like to learn. There seem to be some output but what I expected is a vector of z values. Thank you so much for any help given.
newton.inputsingle <-
2002 May 14
1
Functional Data Analysis
Hi,
is there support (i.e. packages or similar) in R for functional data
analysis as suggested by Ramsay (1982) and Besse and Ramsay (1986)?
Cheers
Roland
--
E-Mail : Roland.Goecke at ieee.org
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r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or
2004 Dec 14
1
increase thr range in R
Hello Everybody in order to get some needed results out of my function i
need to get my besselI function evaluated at some values which normally gave
Inf or 0 (expon.scaled NAN) back. So I would like to increase the range in R
from approxamittly 1e+320 to aabout 1e+500 or something like that. Is there
any possibility or pacckage to do this easily?
Thank You
Sebastian Kaiser
Institut for Statistics
2010 Jun 15
0
nlm is
Hello,
I am trying to compute MLE for non-Gaussian AR(1). The error term follows a difference poisson distribution. This distribution has one parameter (vector[2]).
So in total I want to estimate two parameters: the AR(1) paramter (vector[1]) and the distribution parameter.
My function is the negative loglikelihood derived from a mixing operator.
f=function(vector)
2010 Feb 09
1
how to adjust the output
Hi R-users,
I have this code below and I understand the error message but do not know how to correct it. My question is how do I get rid of “with absolute error < 7.5e-06” attach to value of cdf so that I can carry out the calculation.
integrand <- function(z)
{ alp <- 2.0165
rho <- 0.868
# simplified expressions
a <- alp-0.5
c1 <-
2002 Oct 17
1
underflow handling in besselK (PR#2179)
The besselK() function knows about overflows/underflows internally;
there is a constant xmax_BESS_K in src/nmath/bessel.h (and referred to
only in bessel_k.c), equal to 705.342, which is checked if expon.scaled is
FALSE. (The equivalent number for bessel_i.c is 709, defined as
exparg_BESS in bessel.h.) However, besselK(x) silently returns +Inf if
x>705.342. This behavior is reasonable for
2002 Oct 23
1
vectorizing a function
Dear R-xperts
I have just written a little hypergeometric function, included below
[the hypergeometric function crops up when solving a common type of
ODE].
It works fine on single values of the primary argument z, but
vectorizing it is getting confusing.
The best I have come up with so far just tests for z being longer than
1 and if so, uses sapply() recursively. This is fine, except that it