Irregular solid harmonic
= Irregular solid harmonic
{title2=$r^{-n-1}Y_{nm}=r^{-(2n+1)}H_n$}
An <irregular solid harmonic> is harmonic on punctured three-dimensional <Euclidean space> and generally singular at the origin. The <Kelvin transform> maps a degree-$n$ <regular solid harmonic> to a constant multiple of its irregular counterpart.