Vector spherical harmonic
= Vector spherical harmonic
{wiki}
For an angular <spherical harmonic> $Y$ of degree $n\geq1$, the radial, tangential gradient and tangential curl families can be normalized as $\mathbf P=\widehat{\mathbf r}Y$, $\mathbf B=r\nabla Y/\sqrt{n(n+1)}$ and $\mathbf C=-r\widehat{\mathbf r}\times\nabla Y/\sqrt{n(n+1)}$. They depend only on direction. At $n=0$ only the radial family is defined by these formulas.