#tex{{ \bm{A}(x,y,z)=A_x(x,y,z)\bm{i}+A_y(x,y,z)\bm{j}+A_z(x,y,z)\bm{k} }}
#tex{{ \mathrm{grad} \phi &= \nabla\phi\\ &= \left(\bm{i}\frac{\partial}{\partial x}+ \bm{j}\frac{\partial}{\partial y}+\bm{k}\frac{\partial}{\partial z}\right)\phi\\ &= \frac{\partial\phi}{\partial x}\bm{i}+ \frac{\partial\phi}{\partial y}\bm{j}+\frac{\partial\phi}{\partial z}\bm{k} }}
物理数学公式集では三角関数や特殊関数など…