Yes,
You have probably read this: http://www.gnu.org/software/gsl/manual/html_node/Overview-of-Nonlinear-Least_002dSquares-Fitting.html#Overview-of-Nonlinear-Least_002dSquares-Fitting
What is required from you is to provide two functions
the objective:
`
int sine_f (const gsl_vector * x, void *data,
gsl_vector * f){
...
for(...){
...
double Yi = A * sin(B*t +C);
gsl_vector_set (f, i, (Yi - y[i])/sigma[i]);
}
...
}
and then the derivative of the objective with respect to the parameters
int
sine_df (const gsl_vector * x, void *data,
gsl_matrix * J)
//the derivatives of Asin(Bt +C) wrt A,B,C for each t
This is straight from http://www.gnu.org/software/gsl/manual/html_node/Example-programs-for-Nonlinear-Least_002dSquares-Fitting.html#Example-programs-for-Nonlinear-Least_002dSquares-Fitting
So the Jacobian is just a 3xN matrix, where N is the number of data points For example J(0,3) = sin(B*t_3 + C)
if A,B,C correspond to x[0],x[1],x[2]
And J(1,5) = A*t_5*cos(B*t_5 + C) This is the derivative wrt. B