Illes, > The 3 variables represent biochemical concentrations normalized to the > interval [0,1]. Can I tell the solver (or another solver) that it should > stay inside this interval? I keep receiving solutions outside this interval, > which are mathematically OK, but biochemically really nonsense.
Ah... constrained Newton iteration is another matter. I'd suggest doing some reading to find appropriate numerical techniques. I am uncertain if GSL has a canned solution for you. Googling or hitting the journals for "Newton iteration inequality constraint" should give you lots of places to look. >From reading other responses to this message, it does seem like futzing by adding penality terms could get somewhere. If you do get it to work, you'll have a scheme that'll solve your specific three-concentration problem. If you learn and implement the general constrained approach, then you'll know a scheme that'll solve the whole class of problems. As a last thought, C and GSL probably aren't the best tools if you're exploring algorithms. - Rhys
