Displaying 20 results from an estimated 1584 matches for "gamma".
2001 Dec 13
2
inconsistency between gamma and choose functions
Please can someone explain why I seem to get these contradictory results?
choose(5,2)
[1] 10
gamma(6)/(gamma(3)*gamma(4))
[1] 10
gamma(6)/(gamma(3)*gamma(4)) == choose(5,2)
[1] TRUE
# all's well so far.
# now look what happens:
gamma(21)/(gamma(6)*gamma(16)) == choose(20,5)
[1] FALSE
# check individual terms:
gamma(21)/(gamma(6)*gamma(16))
[1] 15504
choose(20,5)
[1] 15504
# so they are the...
2005 Oct 31
2
nls() fit to Kahnemann/ Tversky function
Dear WizaRds,
I would like to fit a curve to ten points with nls() for one
unknown parameter gamma in the Kahnemann/ Tversky function, but somehow
it won't work and I am unable to locate my mistake.
p.kum <- seq(0.1,1, by=0.1)
felt.prob.kum <- c(0.16, 0.23, 0.36, 0.49, 0.61, 0.71, 0.85, 0.89, 0.95,
1) ## how to find a function that fits these points nicely?
plot(p.kum, felt.prob.kum...
2017 Aug 09
2
Package nleqslv ERROR
...iculty in understanding an error i get when running a code to solve a system of non-linear equations, with four equations and two variables.
This is my code:
ALPHA <- c(-0.0985168033402, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4)
BETA <- c(-0.0985168033402, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4)
GAMMA <- c(0.3940672148378, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4)
MEA <- 30000
MIA <- 10000
MAA <- 50000
DEA <- 0.385
fun <- function(x) {
f <- numeric(length(x))
f[1] <- 1*x[1] - ((((MEA*((0.5*((MIA-MEA)^2))^(-BETA[1+j]))*((0.5*((MAA-MEA)^2))^(-ALPHA[1+i]))*((DEA)^(-GAMMA...
2010 Apr 15
2
using nls for gamma distribution (a,b,d)
Dear all
i want to estimated the parameter of the gamma density(a,b,d)
f(x) = (1/gamma(b)*(a^b)) * ((x-d)^(b-1)) * exp{-(x-d)/a)} for x>d
f(x) = Age specific fertility rate
x = age
when i run this in R by usling nls()
gamma.asfr <- formula(asfr ~ (((age-d)^(b-1))/((gamma(b))*(a^b)))*
exp(-((age-d)/a)))
gamma.asfr1 <- nls(gamma.asfr, data= a...
2008 Nov 19
1
F-Tests in generalized linear mixed models (GLMM)
Hi!
I would like to perform an F-Test over more than one variable within a
generalized mixed model with Gamma-distribution
and log-link function. For this purpose, I use the package mgcv.
Similar tests may be done using the function "anova", as for example in
the case of a normal
distributed response. However, if I do so, the error message
"error in eval(expr, envir, enclos) : object "...
2005 Jun 24
1
interpreting Weibull survival regression
Hi,
I was wondering if someone can help me
interpret the results of running
weibreg.
I run the following and get the
following R output.
> weibreg(Surv(time, censor)~covar)
fit$fail = 0
Call:
weibreg(formula = Surv(time,
censor)~covar)
Covariate Mean Coef
Rel.Risk L-R p Wald p
covar 319.880 -0.002 0.998
0.000
log(scale) 0.000 8.239
2009 Oct 21
2
How to average subgroups in a dataframe? (not sure how to apply aggregate(..))
Dear all,
Lets say I have the following data frame:
> set.seed(1)
> col1 <- c(rep('happy',9), rep('sad', 9))
> col2 <- rep(c(rep('alpha', 3), rep('beta', 3), rep('gamma', 3)),2)
> dates <- as.Date(rep(c('2009-10-13', '2009-10-14', '2009-10-15'),6))
> score=rnorm(18, 10, 3)
> df1<-data.frame(col1=col1, col2=col2, Date=dates, score=score)
col1 col2 Date score
1 happy alpha 2009-10-13 8.120639
2 happy alph...
2011 Oct 12
2
Nonlinear regression aborting due to error
Colleagues,
I am fitting an Emax model using nls. The code is:
START <- list(EMAX=INITEMAX, EFFECT=INITEFFECT, C50=INITC50)
CONTROL <- list(maxiter=1000, warnOnly=T)
#FORMULA <- as.formula(YVAR ~ EMAX - EFFECT * XVAR^GAMMA / (XVAR^GAMMA + C50^GAMMA)) ## alternate version of formula
FORMULA <- as.formula(YVAR ~ EMAX - EFFECT / (1 + (C50/XVAR)^GAMMA))
FIT <- nls(FORMULA, start=START, control=CONTROL, trace=T)
If GAMMA equals 10-80, nls converges successfully and the fit tracks the fit from a smoother (Supe...
2010 Aug 18
1
Displaying Results in Two Columns
Could I have some suggestions as to how (various ways) I can display my confidence interval results?
rm(list = ls())
set.seed(1)
func <- function(d,t,beta,lambda,alpha,p.gamma,delta,B){
d <- c(5,1,5,14,3,19,1,1,4,22)
t <- c(94.32,15.72,62.88,125.76,5.24,31.44,1.048,1.048,2.096,10.48)
post <- matrix(0, nrow = 11, ncol = B)
theta <- c(lambda,beta)
beta.hat <- 2.471546
for(j in 1:B){
for(i in 1:(B-1)){
c.lambda <- rgamma(10,d+alpha,t+beta.hat)...
2010 Jun 16
2
Fitting Gamma distribution
I'm looking for goodness of fit tests for gamma distributions with large data
sizes and for different data.
I have a matrix with around 4.000 data values in it and i have fitted a
gamma distribution with "fitdistr".
You can see the example:
> fitdistr(corpo,"gamma",lower=0.001)
Errore in optim(x = c(5000, 5000, 5000...
2004 May 12
1
Sem error - subscript out of bounds
What??s happening with this following code:
require(sem)
Celpe.Mod.RAM <- matrix(c(
# path parametro Inicio
"Produ????o -> T1", "gamma.11", NA,
"Produ????o -> T2", "gamma.12", NA,
"Produ????o -> T3", "gamma.13", NA,
"Produ????o -> T4", "gamma.14...
2011 Feb 09
3
precision of gamma function
Dear R users,
I have to calculate gamma functions for negative numbers beyond -171.4.
e.x. gamma(-500.4)
I got following:
> gamma(-170.4)
[1] -5.824625e-308
> gamma(-171.4)
[1] 0
Warning message:
underflow occurred in 'gammafn'
I have tried to use a recursion getting values a little futher -180.
How could I solve this pro...
2008 Jun 11
2
MLE Estimation of Gamma Distribution Parameters for data with 'zeros'
...hole.
Lower bound is 0 (no fractures in the selected data interval), and upper
bound is ~ 10 - 50, depending on what scale you are conducting the
analysis on.
I read in the data from a text file, convert it to numerics, and then
calculate initial estimates of the shape and scale parameters for the
gamma distribution from moments. I then feed this back into the
fitdistr() function.
R code (to this point):
########################################
data.raw=c(readLines("FSM_C_9m_ENE.inp"))
data.num <- as.numeric(data.raw)
data.num
library(MASS)
shape.mom = ((mean(data.num))/ (sd(data.num...
2011 Feb 25
5
Substituting inside expression
I am having following problem:
I?m constructing model for calculation of area of triangle.
I know sides a, b, and gamma angle.
I wish to calculate the area using heron?s formula:
S <- sqrt(s*(s-a)*(s-b)*(s-c))
where
s <- (a+b+c)/2
and c is calculated using law of cosines:
c <- sqrt(a^2 + b^2 -2*a*b*cos(gamma))
since i am calculating a regression model, i need derivation of this
expression for area S.
somet...
2017 Aug 09
0
Package nleqslv ERROR
...error i get when running a code to solve a system of non-linear equations, with four equations and two variables.
>
> This is my code:
>
> ALPHA <- c(-0.0985168033402, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4)
> BETA <- c(-0.0985168033402, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4)
> GAMMA <- c(0.3940672148378, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4)
> MEA <- 30000
> MIA <- 10000
> MAA <- 50000
> DEA <- 0.385
> fun <- function(x) {
> f <- numeric(length(x))
> f[1] <- 1*x[1] - ((((MEA*((0.5*((MIA-MEA)^2))^(-BETA[1+j]))*((0.5*((MAA-MEA)^2...
2009 Dec 11
3
how can generate from trunceted gamma distribution in R ?
Hi, all
How can generate a sample from truncated inverse gamma distribution in R?
thanks
2004 Jul 03
1
samba+obsd+subnets
...to my problems/setup, and I've also googled my ass off :(
So here I am, resorting to you guys in hope of help =] Sorry to say, but I
don't have much experience, and therefore I'm a bit lost at the moment. Not
sure what exactly to do to straighten this out.
So, my setup is as follows:
GAMMA 192.168.1.2
|
| 192.168.1.1
[Clavister FW]
| 192.168.0.1
|
ALFA 192.168.0.3
Client1-N DHCP
I've left out a number of irrelevant boxes. Everything of this is connected
through a switch, but is div...
2013 Mar 26
2
NaNS Error Message
...of calculation and I have gotten several
warnings that say "NaNS produced". Whatever I could read on line gives me
an idea that this warning is produced when the number is use is a negative
log or otherwise mathematically problematic.
I'm getting this error while using factorial() and gamma () on strictly
positive numbers (always greater than zero).
Here is a snippet of my code:
k goes from 1 to a positive limit.
S is always 100.
Only positive values of n are allowed into the loop.
if(n>0)
{
while(k<=lim)
{
sn<-(S-n);snfact<-gamma(sn);
sn2<-(2...
2006 Sep 01
1
integration problem with gamma function
...es for easy
reproduction) and can be pasted directly into R. The problematic part
(which is included below of course) is
<--- Original Mathematica --->
(* p_svbar *)
UiA = Ni (Dsi - 2Di A + A^2)/2;
UiiA = Nii (Dsii - 2Dii A + A^2)/2;
psvbar = NIntegrate[1/(UiA^(Ni/2)) 1/(UiiA^(Nii/2))
Gamma[Ni/2,UiA/(sH^2),UiA/(sL^2)]
Gamma[Nii/2,UiiA/(sH^2),UiiA/(sL^2)],{A,L,H},
MinRecursion->3];
PSVbar = psvbar/(4 Log[sH/sL]);
Print["p(s?v|D_1D_2I) = const. ",N[PSVbar,6]];
</--->
<--- translation to R --->
integpsvbar <- function(A)
{
# Mathematica: gamma[a,z0,z...
2005 Dec 05
3
The gamma function and infinity
I have to calculate some formula like:
gamma(x)/(gamma(x+y)
and I observed that for relatively big values of x, R
returns infinity and so cannot compute the formula. Is
it possible to force R to give the real value of
gamma(x) instead of Inf ?
thanks