例題 ベクトル場${\bf F}$の回転を求めよ.

$\displaystyle {\bf F} = z{\bf i} + x^2{\bf j} + 2y{\bf k}$

解答 ベクトル場の回転は次のように定義します.

$\displaystyle \rm {curl} \boldsymbol{F} = \nabla \times \boldsymbol{F} = \left(...
...al F_{2}}{\partial x} - \frac{\partial F_{1}}{\partial y}\right)\boldsymbol{k} $

形式的に

$\displaystyle \nabla \times \boldsymbol{F} = \left\vert\begin{array}{ccc}
\bol...
...rac{\partial
}{\partial z}\\
F_{1} & F_{2} & F_{3}
\end{array} \right\vert $

と表わします.

$\displaystyle {\rm curl} \boldsymbol{F} = \left\vert\begin{array}{ccc}
\boldsy...
... \end{array} \right\vert = 2\boldsymbol{i} + \boldsymbol{j} + 2x\boldsymbol{k}
$