# Re: [R] problem using uniroot with integrate

From: Ken Knoblauch <knoblauch_at_lyon.inserm.fr>
Date: Thu 10 Mar 2005 - 06:19:30 EST

best,

Quoting Sundar Dorai-Raj <sundar.dorai-raj@pdf.com>:

>
>
> 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
>

Ken Knoblauch
Inserm U 371
Cerveau et Vision
18 avenue du Doyen Lepine
69675 Bron cedex
France
tel: +33 (0)4 72 91 34 77
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