Total differential
= Total differential
{title2=$df$}
For a differentiable scalar function of several variables, the total differential is
$$
df=\sum_i\frac{\partial f}{\partial x_i}\,dx_i.
$$
= Total differential
{title2=$df$}
For a differentiable scalar function of several variables, the total differential is
$$
df=\sum_i\frac{\partial f}{\partial x_i}\,dx_i.
$$