The statement of the problem which you wish to solve is incomplete. It is also necessary to give some form of continuity conditions relating dF1/dR and dF2/dR at R=R2.

Your problem could be solved as a two point boundary value problem where the initial value of dF1/dR at R=R1 is unknown, but has to be iterated upon so that F2(R3)=P2 is satisfied. The only difficulty will be the making sure that once your code has integrated as far as R=R2, and has calculated the values of F1 and dF1/dR at that point, that the correct values of F2 and dF2/dR are then defined so that the rest of the computation from R2 to R3 is undertaken.

I don't know how easy it is to persuade matlab to do this, but it is fairly straightforward with one's own self-written Fortran code.

I think that it is also possible to write down the general solution of this problem in integral form. This might be the better way to go.

D. Andrew S. Rees

Hi again,

Thanks a lot dear Andrew