Extended Convergence Checking
Primarily internal code for checking optimization convergence, see convergence for a more detailed discussion.
checkConv(derivs, coefs, ctrl, lbound, debug = FALSE)
derivs: typically the "derivs" attribute of optimizeLmer(); with "gradients" and possibly "Hessian" component
coefs: current coefficient estimates
ctrl: list of lists, each with action character strings specifying what should happen when a check triggers, and tol numerical tolerances, as is the result of lmerControl()$checkConv.
lbound: vector of lower bounds for random-effects parameters only
(length is taken to determine number of RE parameters)
debug: enable debugging output, useful if some checks are on "ignore", but would "trigger"
A result list containing - code: The return code for the check
convergence