Estimation of continuous functions is done using maximum marginal likelihood estimation via Template Model Builder.
To install StockRecruitSET, first install TMB from CRAN, then install StockRecruitSET via
devtools::install_github("mebrooks/stockrecruit/StockRecruitSET", build_opts = c("--no-resave-data", "--no-manual"))
You may need to install the devtools package, compiler tools, and other dependencies first. To install TMB, it may be necessary to install the version of Rtools that matches your version of R.