thank you for your answer.
I want to do this in order to reduce the computation time required for numerical solution of nonlinear heat equation with Robin’s condition on one of the boundaries:
BC1 du(0,t)/dx=f4(u) at x=0
BC2 u(1,t)=Const1 at x=1
I need lower dx in the vicinity of x=0 (where u changes rapidly) than at the rest of the interval (where it changes slowly).
My knowledge is insufficient, so for the moment I do it in a “dumb” way: solve the problem by steps, starting from a smaller interval x=0…L1 with small spacestep, and increase the interval (increase L1) as soon as u(L1/2) starts to vary noticeably.
I believe there must be a better solution included in Maple.