This looks an awful lot like you are trying to solve for d' in an
m-alternative forced choice experiment for an unbiased observer. Try
the function dprime.mAFC from the psyphy package. For comparison with
your example, it's code is:
psyphy:::dprime.mAFC
function (Pc, m)
{
m <- as.integer(m)
if (m < 2)
stop("m must be an integer greater than 1")
if (!is.integer(m))
stop("m must be an integer")
if (Pc <= 0 || Pc >= 1)
stop("Pc must be in (0,1)")
est.dp <- function(dp) {
pr <- function(x) dnorm(x - dp) * pnorm(x)^(m - 1)
Pc - integrate(pr, lower = -Inf, upper = Inf)$value
}
dp.res <- uniroot(est.dp, interval = c(-10, 10))
dp.res$root
}
<environment: namespace:psyphy>
Hope that helps,
best,
Ken
On Sat, May 27, 2017 at 9:16 AM, Neetu Shah <nshah.0452 at gmail.com>
wrote:
Dear Sir/Ma'am,
I am trying to make a function to solve an equation that is given
below:
findH <- function(p_star, k){
fun <- function(y){
(pnorm(y+h))^(k-1)*dnorm(y)
}
lhs <- integrate(fun, -Inf, Inf)$value
return(uniroot(lhs, lower = -10, upper = 10,
tol = p_star)$root)
}
In lhs, I integrated a function with respect to y and there would be an
unknown h that I need to find.
I need to equate this lhs to p_star value in order to find h. Which
function should I use to solve this equation?
Please guide me regarding this.
Thank you.
--
With Regards,
Neetu Shah,
B.Tech.(CS),
3rd Year,
IIIT Vadodara.
--
Kenneth Knoblauch
Inserm U1208
Stem-cell and Brain Research Institute
18 avenue du Doyen Lépine
69500 Bron
France
tel: +33 (0)4 72 91 34 77
fax: +33 (0)4 72 91 34 61
portable: +33 (0)6 84 10 64 10
http://www.sbri.fr/members/kenneth-knoblauch.html
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