Finite Element Methods for Maxwell's Equations
《Finite Element Methods for Maxwell's Equations》 · 第 237 页 · Section 12.2「The True Asymptotics for Special Sifting Functions」
For $s>1$ we have $\Phi(x,x^{1/s})\sim s\omega(s)x(\log x)^{-1}$ as $x\to\infty$ where $\omega(s)$, the Buchstab function, is the continuous solution to $s\omega(s)=1$ if $1\le s\le2$ and $(s\omega(s))'=\omega(s-1)$ if $s>2$.