Solution
= Solution
With $y=q^{-1/4}e^{\lambda S}$, leading order gives $S'=\pm i\sqrt q$ and the transport equation gives the $q^{-1/4}$ amplitude. Superposition yields the stated <WKB approximation> form.
= Solution
With $y=q^{-1/4}e^{\lambda S}$, leading order gives $S'=\pm i\sqrt q$ and the transport equation gives the $q^{-1/4}$ amplitude. Superposition yields the stated <WKB approximation> form.