add Omega correlations to a parameter table
addOmegaCorr(pars, by = NULL, as.fun)
A parameter table, like returned by `NMreadExt()`.
The name of a column, as a string. Calculate the correlations within a grouping variable? This will often be a column containing the model name.
See `?NMdataConf`
The parameter table with a `corr` column added.