Thanks. I was able to get this to work on my sample problem, with the following combination: the number of parameters to be fit nfit = 3. the number of parameters for the function npars = 4 (the first 3 are the ones to be fit) set f.p = nfit; gsl_vector length npars gsl_matrix *covar = gsl_matrix_alloc (nfit, nfit); s = gsl_multifit_fdfsolver_alloc (T, n, npars); gsl_multifit_fdfsolver_set (s, &f, &x.vector); the functions f.f and f.df use all four parameters, but the fourth is treated as a constant. No error messages about vector length and the result on a test is 'correct.' Thanks for your help. Regards, Ken McF
________________________________ From: Martin Jansche [mailto:[EMAIL PROTECTED] Sent: Sun 7/30/2006 1:58 PM To: McFarlane Kenneth Cc: [email protected] Subject: Re: [Help-gsl] Additional parameters in Non-linear least-squares fitting? On 7/30/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > I need to pass additional parameters to the functions used by the N-L L-S > fitting > routines. The functions I want to fit may have 6 parameters but I want to > vary > only 3 during the fit. This means that, as far as the GSL API is concerned, you want to fit a function with three parameters. Additional parameters can be passed via the void *params argument of the component f of the structure gsl_multifit_function. You may want to write one or more wrapper routines that take a vector of parameters plus a boolean vector indicating which parameters you want to vary as arguments and return an appropriate gsl_multifit_function. Regards, -- mj ====================================================================== The information contained in this message is intended only for the recipient, and may otherwise be privileged and confidential. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, please be aware that any dissemination or copying of this communication is strictly prohibited. If you have received this communication in error, please immediately notify us by replying to the message and deleting it from your computer. This footnote also confirms that this email has been scanned for all viruses by the Hampton Universitys Center for Information Technology Enterprise Systems service. _______________________________________________ Help-gsl mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-gsl
