Re: [Help-gsl] Multifit and GSL_CONTINUE

[Brian Gough]

At Mon, 7 Dec 2009 15:48:38 -0700,
Zach wrote:
> 
> Since it is returning GSL_CONTINUE, is there a way to ask it to continue?
> If not, then it should be returning some other code, preferably one that
> indicates failure, correct?  In the example program, it would explicitly
> break out of the user iteration loop upon a GSL_CONTINUE return from
> gsl_multifit_fdfsolver_iterate.  Or, is it perhaps the case that the return
> value of gsl_multifit_fdfsolver_iterate should not be interpreted as a enum
> type found in err/gsl_err.h, despite the source seeming to use that
> definition?

Hi,

Thanks for your email (I agree that the name GSL_CONTINUE is confusing
here).  There was a previous bug report, logged at
https://savannah.gnu.org/bugs/?25383 

Following the bug report, I added the following text to the manual:

    The possible error codes are,

    ... 

    @item GSL_CONTINUE
    the routine has made 10 or more attempts to find a suitable trial step
    without success (but subsequent calls can be made to continue the search).

To summarise GSL_CONTINUE should normally be treated as an error,
although it is possible to try making further calls to
gsl_multifit_fdfsolver_iterate from that point (without any guarantee
that there will be any progress).

I plan to change it to GSL_ENOPROG but I did not do that straight away
as I was concerned it might create compatibility problems.

-- 
Brian Gough

GNU Scientific Library -
http://www.gnu.org/software/gsl/