Help with ODE solver

[Marco Antoniotti]

Hi

I am using the LSODE solver for my research and now need to do the
following.

At a time t_i, I need to change the value of one (or more) of the
variable(s) involved.

I think I understand I have two avenues to follow to achieve this
goal, but, given my inexperience with Octave (and/or Matlab) I don't
know which is the best one.

1 - I could insert a specific test in the derivative function

  function xdot = f(x, t)
    xdot = zeros(rows(x), 1);

    if (t == t_i)
       ## set x(k) to M
    endif

    xdot(1) = ...
    ...
    xdot(n) = ...

  endfunction


2 - I could break down the integration into intervals and set the
    variable value between integrations.

I'd like some comments about what would be the "best" (for an
approrpiate definition of "best") way to achieve this goal.

Thanks

-- 
Marco Antoniotti ========================================================
NYU Courant Bioinformatics Group        tel. +1 - 212 - 998 3488
715 Broadway 10th Floor                 fax  +1 - 212 - 995 4122
New York, NY 10003, USA                 http://bioinformatics.cat.nyu.edu
                    "Hello New York! We'll do what we can!"
                           Bill Murray in `Ghostbusters'.



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