Re: [Help-gsl] fitting example

[Brian Gough]

At Tue, 18 Jul 2006 20:48:39 +0200 (CEST),
Petr Ent wrote:
> i understand it that you should compute the value of your function to be 
> fitted with current results (x vector) and store it to vector f. but in this 
> example, you do that + substract "real value" (y_i) from it and divide it by 
> deviation (sigma_i).
> 
> gsl_vector_set (f, i, (Yi - y[i])/sigma[i]);
> 
> why do you do that? and what if you dont know deviation of data to be fitted?

The fitting minimises the residual vector, model - data, and this is
what the function has to provide.  

For data with unknown errors, set sigma = 1.

-- 
best regards,

Brian Gough

Network Theory Ltd,
Publishing the GSL Manual - http://www.network-theory.co.uk/gsl/manual/