Second Focus

Remeber the post "My Own Wave equation", dated 20 Nov 2014, where

$\cfrac{\partial \psi}{\partial x}\cfrac{\partial \psi}{\partial t}=\cfrac{c^2p}{\sqrt{2}}.\cfrac{\partial^2\psi}{\partial x^2}.e^{-i\pi/4}$

On several occasions where $\psi$ rests on a parabola contour/generated surface with $\cfrac{\partial^2\psi}{\partial x^2}=0$ at the focus, the resulting zero coefficient before $e^{-i\pi/4}$ removes the phase lag and so removes the delay in the change of $\psi$ in time.

A second focus is possible,

A magnetic coil deformed to provide such a focus will not have a phase lag in its response at the focus also.

This was left unsaid after ultra-bright LEDs, detection points, jet engines, under-water jets, etc.

Hello!