ABSTRACT
Partial derivatives. Suppose function f (x; y) is dened on X R2. Let us keep one of the independent coordinates, let say y, xed and consider the function of one variable g (x) = f (x; y0). If this function is dierentiable at x0, then the derivative g
0 (x0) is called the partial derivative of f (x; y) with respect to x at the point (x0; y0). The following notations are common: fx (x0; y0) @xf (x0; y0) @1f (x0; y0) @f@x (x0; y0). The specication of the point is frequently omitted if it is clear from the context. In the same way can be dened the partial derivative with respect to y.
