As others will tell you: you need to provide a reproducible example.
What are p1, u1, u2 ?
<quote>
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
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
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