From: Stanislaw Szpala <sszpala@im...>  20030827 20:16:03

Hi, I'm using vnl_levenberg_marquardt class to fit my data set (I supply no = gradients). I run the code from Microsoft Visual C++ 6.0; no MFC = classes, Windows2000. It works, but I need to get an estimate of the = errors of the fitted parameters. I believe the errors can be taken from = the diagonal elements of the covariance matrix. Unfortunately, I am = unable to get the covariance matrix using get_covariance(), see below.=20 ... vnl_vector<double> x0(3); ... vnl_vector<double> x1 =3D x0; vnl_levenberg_marquardt lm(fittedFunction); lm.minimize_without_gradient(x1); vnl_matrix<double> covar(3,3); covar =3D lm.get_covariance(); ('fitedFunction' is my class derived from 'vnl_least_squares_function', = and it defines the fitted function 'f') When I try accesing get_JtJ(), I get "not implemented yet" message, see: jacobian =3D lm.get_JtJ(); So it looks like it is not implemented. But the Jacobians must be = calculated at some point. So, how can I access the covariance matrix? Thanks, Stan Stanislaw Szpala, Ph.D. Robarts Research Institute 100 Perth Drive London Ontario N6A 5K8, Canada tel (519)6635777x34213 sszpala@... 