Partial Derivative -- from Wolfram MathWorld
mathworld.wolfram.com › PartialDerivativeJan 19, 2022 · (partialf)/(partialx_m)=lim_(h->0)(f(x_1,...,x_m+h,...,x_n)-f(x_1,...,x_m,...,x_n))/h. (1) The above partial derivative is sometimes denoted f_(x_m) for brevity. Partial derivatives can also be taken with respect to multiple variables, as denoted for examples (partial^2f)/(partialx^2) = f_(xx) (2) ...