# Partial derivatives

In the same way as there exist derivatives of functions of one variable, there are also derivatives of functions of two variables. However, since we deal with two variables, we have to indicate with respect to which variable we differentiate. These derivatives of functions of two (or more) variables are called partial derivatives.

In this section we explain how one can determine these partial derivatives and how one can use them to approximate a change in the function value for small changes in the input variables.