Return the data frame containing the gradients for all parameters.
gradients()A list of lists. See Examples.
# \dontrun{
test <- cmdstanr_example("logistic", method = "diagnose")
# retrieve the gradients
test$gradients()
#> param_idx value model finite_diff error
#> 1 0 -1.956090 42.51440 42.51440 -1.09401e-08
#> 2 1 -0.130427 -13.33070 -13.33070 -1.40895e-08
#> 3 2 1.228760 -24.25270 -24.25270 -4.45662e-08
#> 4 3 0.625050 3.12825 3.12825 -3.33963e-09
# }