c - no update of parameters using multirootsolver -

c - no update of parameters using multirootsolver -

i trying write code solve non linear scheme of equations. using functions of gsl library, more multiroot_fdf_solver. problem doesn't want converge. more specifically, have next behavior:

-if initial conditions close result, gsl_multiroot_fdf_solver_iterate not update parameters @ all. tried display results on different steps, , have parameters dx = nan (i think quite srange), status of gsl_multiroot_fdf_solver_iterate "success" , status of gsl_multiroot_test_residual "the iteration has not converged yet"

-the parameters updated if initial conditions far expected result. obvisously in case not converge right values.

i have checked multiple times look of function , jacobian, , seem good.

i have precise jacobian (and scheme well) quite complicated look many trigonometric function.

would have thought of be? possible if look of jacobian complicated, has troubles compute it? give thanks in advance answers, stucked @ point.

c gsl nonlinear-optimization