option determining when differences between the analytic gradient and its finite difference approximation are flagged as an error.
check_derivatives_print
option related to the amount of output. 'all' means that all comparisons are shown, 'errors' only shows comparisons that are flagged as an error, and 'none' shows the number of errors only.
func_grad_name
option to change the name of the gradient function that shows up in the output.
...
further arguments passed to the functions func and func_grad.