nlxb or nlfb from package
nlmrt.
"summary"(object, ...)summary.nlmrt performs a summary method for an object of class 'nlmrt' that
has been created by a routine such as nlfb or nlxb for nonlinear
least squares problems. Issue: When there are bounded parameters, nls returns a Standard Error for each of
the parameters. However, this summary does NOT have a Jacobian value (it is set to 0)
for columns where a parameter is masked or at (or very close to) a bound. See the
R code for the determination of whether we are at a bound. In this case,
users may wish to look in the inst/dev-codes directory of this package,
where there is a script seboundsnlmrtx.R that computes the nls()
standard errors for comparison on a simple problem.
Issue: The printsum() of this object includes the singular values of the Jacobian. These are displayed, one per coefficient row, with the coefficients. However, the Jacobian singular values do NOT have a direct correspondence to the coefficients on whose display row they appear. It simply happens that there are as many Jacobian singular values as coefficients, and this is a convenient place to display them. The same issue applies to the gradient components.
nls(), packages optim and optimx.