nls error in formula

Anaid Diaz wrote:

Hi,
I'm a new R user, with a lot of questions. At the
moment I'm stoped on an error traying to fit a

model:

x <- sandeel ## numeric data (2500-60000)
y <- Noss   ## numeric data  (0-1.2)
A <- 0.8
B <- 0.6
C <- 1/40000
nls( y ~ A-B*exp(-C*x))

Error in match.call(definition, call, expand.dots)

: 

        .Primitive... is not a function

I'm not sure if the error is due to the formula

sytax

or something else.
I'll appreciate any help

Sylvia

Use

nls(y ~ A -B*exp(-C*x), start = c(A = 0.8, B = 0.6,
C = 1/40000))

instead or, preferably,

nls(y ~ SSasymp(x, Asym, R0, lrc))

and read

?SSasymp

for an interpretation of the estimated parameters.