In the mathematical field of differential calculus, a total derivative or full derivative of a function of several variables, e.g., , , , etc., with respect to an exogenous argument, e.g., , is the limiting ratio of the change in the function's value to the change in the exogenous argument's value (for arbitrarily small changes), taking into account the exogenous argument's direct effect as well as its indirect effects via the other arguments of the function.