I consider a PDE system (?pdsolve,numeric)

PDE := {diff(u(x,t),t)=-1/20*diff(v(x,t),x,x),

diff(v(x,t),t)=diff(u(x,t),x,x)}:

IBC := {u(x,0)=sin(Pi*x), u(0,t)=0, u(1,t)=0,

v(x,0)=1-x, v(0,t)=1, v(1,t)=0}:

pds := pdsolve(PDE, IBC, numeric, spacestep=1/50);

Suppose, I need to use the data diff(u(x,t),x,x) or diff(v(x,t),x,x) at x=0.