At Sun, 31 Aug 2008 10:25:26 +0300, Tuomo Keskitalo wrote: > I have been writing a non-linear equation solver based on a modified > Newton iteration method, and a question about failures has come up. What > value should the non-linear equation solver return to the stepper (and > from there to user) in the case that the method reaches a maximum number > of Newton iterations and therefore fails? GSL_CONTINUE or GSL_FAILURE or > something else?
I'd suggest GSL_FAILURE to start with. Hopefully the solver won't fail that often. > which values of variables y should a stepper which uses step doubling > for error estimation return: The values from the single step or the > values from two half steps? You would expect to get the values of single > step from "a stepper", but the values from two half steps should be more > accurate, and they are available. The final value of y should come from the two half steps as they are more accurate. See rk4.c for an example and the error estimate. -- Brian Gough
