On 03.09.2011 18:31, li li wrote:
Dear all,
I forgot to mention the values for the parameters in the first email.
u1<- -3
u2<- 4
alpha<- 0.05
p1<- 0.15
Thank you very much.
2011/9/3 li li<hannah....@gmail.com>
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,
tol = 0.0001)$root
The result is 0 as shown below.
th
[1] 0
No surprise, since
Fp2(0) is 0. And uniroot is finished then and does not need to evaluate
at a lower starting at some positive value such as:
uniroot(Fp2, lower=1e-7, upper=1, tol=1e-7)
# 0.009521749
Uwe Ligges
However, there should be a root between 0.00952 and 0.00955, since the
function values are of opposite signs as below.
Fp2(0.00952)
[1] 2.264272e-05
Fp2(0.00955)
[1] -0.0003657404
Can any one give me a hand here? Thanks a lot.
Hannah
[[alternative HTML version deleted]]
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
