Displaying 20 results from an estimated 7000 matches similar to: "Some Help Needed"
2007 Mar 27
3
Use of 'defineVar' and 'install' in .Call
Dear all,
[system and version information below]
I am trying to modify a C function for finding the root of an
expression. The function is to be called from R as .Call with input
parameters:
f: expression for which we will find the root
guesses: interval for the solution
stol: tolerance
rho: environment
The original functions I use are:
SEXP mkans(double x) {
SEXP ans;
PROTECT(ans =
2007 Mar 27
3
Use of 'defineVar' and 'install' in .Call
Dear all,
[system and version information below]
I am trying to modify a C function for finding the root of an
expression. The function is to be called from R as .Call with input
parameters:
f: expression for which we will find the root
guesses: interval for the solution
stol: tolerance
rho: environment
The original functions I use are:
SEXP mkans(double x) {
SEXP ans;
PROTECT(ans =
2011 Sep 11
3
(no subject)
Dear all,
Can anyone take a look at my program below?
There are two functions: f1 (lambda,z,p1) and f2(p1,cl, cu).
I fixed p1=0.15 for both functions. For any fixed value of lambda (between
0.01 and 0.99),
I solve f1(p1=0.15, lambda=lambda, z)=0 for the corresponding cl and cu
values.
Then I plug the calculated cl and cu back into the function f2.
Eventually, I want to find the lambda value
2011 Sep 03
3
question with uniroot function
Dear all,
I have the following problem with the uniroot function. I want to find
roots for the fucntion "Fp2" which is defined as below.
Fz <- function(z){0.8*pnorm(z)+p1*pnorm(z-u1)+(0.2-p1)*pnorm(z-u2)}
Fp <- function(t){(1-Fz(abs(qnorm(1-(t/2)))))+(Fz(-abs(qnorm(1-(t/2)))))}
Fp2 <- function(t) {Fp(t)-0.8*t/alpha}
th <- uniroot(Fp2, lower =0, upper =1,
2003 Apr 25
4
Kinderman-Ramage (PR#2846)
Hi,
Our department has detected a bug in the implementation of the
Kinderman-Ramage generator for normal random variates in version
1.7.0, which can be seen from the below R session.
(Consecutive calls for chisq.test(...) always gives p-values very
close to 0.)
We have already encountered this bug in version 1.6.2
The error is in file
R-1.7.0/src/nmath/snorm.c
Here is a patch for this file to
2009 Sep 23
1
Maximum Likelihood Est. regarding the degree of freedom of a multivariate skew-t copula
Hello,
I have a bigger problem in calculating the Maximum Likelihood Estimator regarding the degree of freedom of a multivariate skew-t copula.
First of all I would like to describe what this is all about, so that you can understand my problem:
I have 2 time series with more than 3000 entries each. I would like to calculate a multivariate skew-t Copula that fits this time series.
Notice:
2010 Feb 11
1
histogam plots
Hi all,
I want to draw a histgram for each row of a matrix and compare them.
However the plot I
got does not have the same y range and x range, which makes it difficult to
make the comparison.
Is there a easy way to fix the x range and y range in a xy plot for several
plots, instead of specifying
them for each plot.
The following is my code for generalizing the matrix and draw the
histogram.
2000 Jan 12
1
Usage of p/d/qnorm
Hello,
could You please help: I am looking for a way to formulate test accuracy
measures such as test sensitivity, specificity, predictive values, and
correct classification rate using p/d/qnorm. The tests' primary values
follow a bimodal distribution, which is modelled by a mixture of two normal
distributions:
p * dnorm ((x - u1) / s1) / s1 +
(1 - p) * dnorm ((x - u2) / s2) / s2)
2010 Jun 13
2
help with R
Hi all,
I want to solve the following equation for x with rho <- 0.5
pnorm(-x)*pnorm((rho*dnorm(x)/pnorm(x)-x)/sqrt(1-rho^2))==0.05
Is there a function in R to do this?
Thank you very much!
Hannah
[[alternative HTML version deleted]]
2010 Jun 23
2
question about a program
Dear all,
I have the following program for a multiple comparison procedure.
There are two functions for the two steps. First step is to calculate the
critical values,
while the second step is the actual procedure [see below: program with two
functions].
This work fine. However, However I want to put them into one function
for the convenience
of later use [see below: program with one
2012 Apr 19
3
Bivariate normal integral
hello,
I'm trying to improve the speed of my calculation but didn't get to a
satisfying result.
It's about the numerical Integration of a bivariate normal distribution.
The code I'm currently using
x <-
qnorm(seq(.Machine$double.xmin,c(1-2*.Machine$double.eps),by=0.01),
mean=0,sd=1)
rho <- 0.5
integral <- function(rho,x1){
2012 Apr 07
1
Uniroot error
Dear All
I am trying to find a uniroot of a function within another function (see
example) but I am getting an error message (f()values at end points not of
opposite sign). I was wondering if you would be able to advise how redefine
my function so that I can find the solution. In short my first function
calculates the intergrale which is function of "t" , I need to find the
uniroot of
2011 Mar 29
5
Integration with variable bounds
If this is posted elsewhere I cannot find it. I need to perform multiple
integration where some of the variables are in the bounds of the other
variables. I was trying to use R2Cuba function but cannot set the upper and
lower bounds. My code so far is :
int <- function(y){
u2 = y[1]
z2 = y[2]
u1 =y[3]
z1 = y[4]
ff <- u1*(z1-u1)*u2*(z2-u2)*exp(-0.027*(12-z2))
return(ff)
}
2007 Mar 27
7
Replacement in an expression - can't use parse()
Dear all,
Suppose I have a very long expression e. Lets assume, for simplicity, that it is
e = expression(u1+u2+u3)
Now I wish to replace u2 with x and u3 with 1. I.e. the 'new'
expression, after replacement, should be:
> e
expression(u1+x+1)
My question is how to do the replacement?
I have tried using:
> e = parse(text=gsub("u2","x",e))
> e =
2006 Nov 21
2
Symbolic derivation using D in package stats - how do I properly convert the returned call into a character string?
Dear all,
I am using the function 'D' in the 'stats' package to perform symbolic
derivation.
This works very well and it is much faster than e.g. Mathematica (at
least for my purposes).
First, I would like to thank the development team for this excellent
function.
However, I run into trouble in some cases, particularly when I am to do
some operations on long expressions
2011 Apr 20
2
question regarding qmvnorm
Dear all,
I wrote the following function previously. It worked fine with the old
mvtnorm package.
Somehow with the updated package, I got a error message when trying to use
the function.
I need some help. It is sort of urgent. Can anyone please take a look. The
function is the following.
Thank you very much!
Hannah
library(mvtnorm)
cc_f <- function(m, rho,
2009 Feb 05
1
optimal control, maximization with several variables?
Dear all,
I would like to solve the following problem, which can be done with optimal control theory or dynamic programming:
max(x,y) a*u1+b*u2+c*f1(u2) s.t. 0<u1<x, 0<u2<f2(x,u2), x'=f3(u1,u2,x)
which can be rewritten if optimal control theory should be applied as
H=a*u1+b*u2+c*f1(u2)+lambda*(x') s.t. 0<u1<x, 0<u2<f2(x,u2)
The maximum principle
2012 Dec 06
1
Anomalous outputs from rbeta when using two different random number seeds
Hi, in the code below, I am drawing 1000 samples from two beta
distributions, each time using the same random number seed.
Using set.seed(80) produces results I expect, in that the differences
between the distributions are very small.
Using set.seed(20) produces results I can't make sense of. Around half of
the time, it behaves as with set.seed(80), but around half of the time, it
behaves
2016 Dec 07
4
You have not permission to view content of this location
OS: CentosOS 7
I have installed samba + openldap + smbldap-tools + pam by:
yum --enablerepo=extras install -y epel-release
yum install -y smbldap-tools
yum install -y samba openldap openldap-clients openldap-servers migrationtools
yum install -y nss-pam*
I know that smbldap-tools is a dead project, but I'm interested in it and would like research on it.
I create users and
2008 Feb 19
1
recursive function help
I'm trying to implement a recursive function using integrate, and I
suspect I need a Vectorize somewhere,
but I can't suss it out. Any help would be appreciated. I've tried
traceback() and various debugging ideas to no avail (most likely due to
my inexperience with these tools.)
Here's what I have.
Nk <- function(m, C) {
if (length(m) > 1) {
rho <- C[1, -1]