[Scilab-users] Help with bvodeS & bvode and unusual boundary conditions

[amonmayr at laas.fr]

Hi everyone,

I'm trying to understand how bvodeS works and whether I can use it to 
solve numerically my problem.
A bit of context:
I have a 1D coupled-mode problem, where I model the propagation along 
one direction (let's call it y) of two modes (one in +y-direction and 
one in the -y-direction).
Schematically, it looks like this:

a(0) -->| ODE |-->a(L)
b(0) <--| ODE |<--b(L)

The ODE is of the first order (only a(y), b(y) and a'(y) and b'(y) in 
the ODE, together with non-constant factors).

The thing is that I have scattering-like boundary conditions.
I know the inputs [a(0)=a0;b(L)=bL] and look for the outputs [a(L)=?; 
b(0)=?].
I am of course also interested in  the values of [a(y), b(y)] for all y 
in [0,L], but the puzzling issue are my boundary conditions.
I basically half of my conditions on one side, the other half on the 
other side.
Can I solve such a system using bvodeS?
If I can, how am I supposed to build "zeta" to reflect that my 
conditions only concerns a(0) and b(L)?
Is this doable to get zeta "with holes"?

Thank you in advance for your help,

Antoine