From: Sundar Dorai-Raj <sundar.dorai-raj_at_pdf.com>

Date: Thu 10 Mar 2005 - 04:57:33 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu Mar 10 05:02:52 2005

Date: Thu 10 Mar 2005 - 04:57:33 EST

Ken Knoblauch wrote on 3/9/2005 10:27 AM:

*> Hi,
**>
*

> I'm trying to calculate the value of the variable, dp, below, in the

*> argument to the integral of dnorm(x-dp) * pnorm(x)^(m-1). This
**> corresponds to the estimate of the sensitivity of an observer in an
**> m-alternative forced choice experiment, given the probability of
**> a correct response, Pc, a Gaussian assumption for the noise and
**> no bias. The function that I wrote below gives me an error:
**>
**> Error in f(x, ...) : recursive default argument reference
**>
**> The problem seems to be at the statement using uniroot,
**> because the furntion est.dp works fine outside of the main function.
**> I've been using R for awhile but there are still many nuances
**> about the scoping and the use of environments that I'm weak on
**> and would like to understand better. I would appreciate any
**> suggestions or solutions that anyone might offer for fixing
**> my error. Thank you.
**>
**> dprime.mAFC <- function(Pc, m) {
**> est.dp <- function(dp, Pc = Pc, m = m) {
**>
**> pr <- function(x, dpt = dp, m0 = m) {
**> dnorm(x - dpt) * pnorm(x)^(m0 - 1)
**> }
**>
**> Pc - integrate(pr, lower = -Inf, upper = Inf,
**> dpt = dp, m0 = m)$value
**> }
**>
**> dp.res <- uniroot(est.dp, interval = c(0,5), Pc = Pc, m = m)
**> dp.res$root
**> }
**>
*

Ken,

Look at the argument list for ?uniroot and think "partial matching". You're "m" is being interpretted for "maxiter". Simply change to

dp.res <- uniroot(est.dp, interval = c(0,5), Pc = Pc, m0 = m)

and in other places for consistency and the error goes away. Of course, since you gave no working example, I'm not sure if other errors are present that I'm missing.

--sundar

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu Mar 10 05:02:52 2005

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