[R] simple NLS query

[ivo welch]

dear R experts:  I am trying to orient myself using nls().  so, I am
just trying to copy and adapt an example in the nls() function:

  > d= data.frame( y= runif(10), x= runif(10) )
  > nls( y ~ 1/(1+x), data = d, start= list(x=0.5,y=0.5), trace=TRUE)
  Error in n%%respLength : non-numeric argument to binary operator

the error message seems internal, so it would be nicer if there was a
better error message.  I presume my mistake is so basic that an R
expert sees the problem in 1 second.

(if I manage to figure this one out, my next step will be to learn how
I can get [presumably asymptotic ML] standard errors on estimated
coefficients.  I hope I am looking in the right direction with the
nls() function.)

advice appreciated.

regards,

/ivo