All tidying methods return a data.frame without rownames, whose
structure depends on the method chosen.
tidy returns a data frame with one row per parameter that
was estimated, with columns
parametername of the parameter, or parameter1,
parameter2... if the input vector is not named
valueparameter value that minimizes or maximizes the output
glance returns a one-row data frame with the columns
valueminimized or maximized output value
function.countnumber of calls to fn
gradient.countnumber of calls to gr
convergenceconvergence code representing the error state