Folks,

I am trying to see a pattern when solving 2nd order linear PDE's.

The canonical form for the Hyperbolic case is

$\displaystyle \bar B w_{st}+ \phi(w_s,w_t,s,t,w)=0$ where $\displaystyle \bar B \ne0$

If the discriminant is a real number does the $\displaystyle \phi $ term vanish and hence if the discriminant is some $\displaystyle f(x,y)>0$, do we always have some $\displaystyle \phi $ terms?

And similarly for the elliptical case?

Thanks