Hi, I am new here so I am sorry I do not know exactly how it works to ask questions on this mailing list.
I encounter a problem using the multiroot facility, I tried hard to find solutions anywhere but have not found it yet. I try to briefly describe my problem. I have a quite complex non linear system of 6 equations with 6 parameters to determine. For the moment I will not copy them here because it is a big amount of cosinus and sinus functions (if you require it I can try to do it later). I use multiroot_fdf_solver. I have already checked my Jacobian and my functions multiple times, at this point I do not see any error. My problem is the following: -through iteration, if my initial guess is close to the real values, the parameters(the ones I try to guess) will not update at all, and if I try to display the dx it has the value "NaN". However the status of gsl_multiroot_fdf_solver_iterate is "success". After about 10 iterations, it stops (still in "success" status, and it seems it considers it has converged), and give me as a return the initial guess(but they are not the values I expect). -the parameters will only be updated if my initial parameters are far from their theoretical values. Obviously in this case it does not converge to the good values. At this point the only problem that looks like what I have is described in an (old) thread of this ML called "Possible multiroot shortcoming", I give the link: http://lists.gnu.org/archive/html/help-gsl/2007-08/msg00075.html My question would be: has anyone already had this kind of problem, and do we have some news about the quoted thread because it is really similar to my problem, and I would like to know whether there is a possible "bug" in the multiroot facility because my function is too complicated, or it is me that made an error in my code (as I said I checked it over and over, and I do not find an error yet). Thank you in advance for your answer, and do not hesitate to ask me aditionnal informations if needed, your help would be greatly appreciated!