Model parametersΒΆ
Model parameters are implemented by GModelPar which derives from the abstract GOptimizerPar base class. Each model parameter is factorised into a value and a scale part according to
where \(p\) is the model parameter, \(v\) is the model value factor, and \(s\) is the model scale factor. All three components can be accessed or set via the GModelPar::value(), GModelPar::factor_value(), and GModelPar::scale() methods.
In addition, the class handles parameter errors and gradients as well as parameter minima or maxima. Parameter errors can be accessed or set via the GModelPar::error() and GModelPar::factor_error(), where the former concerns the error on \(p\) while the latter concerns the error on \(v\). Equivalent methods exist for the gradient (GModelPar::gradient() and GModelPar::factor_gradient()), the minimum (GModelPar::min() and GModelPar::factor_min()), and the maximum (GModelPar::max() and GModelPar::factor_max()).
Finally, GModelPar::fix() and GModelPar::free() methods allow to fix or to free a model parameter, and the GModelPar::is_free() and GModelPar::is_fix() methods allow to check whether a parameter is free or fixed.