gRfit are created when the function fit
is applied to a gModel object. When adding new types of
gModel objects, one must also supply the appropritate fit
function. The gRfit object contains the output of the fit which
can be accessed by getFit. Separate print and
summary methods exist for gRfit objects.fit(object, ...)
getFit(x)gRfit as created from fit
applied to a gModel object.fit creates an object of class gRfit.
getFit returns the fit information created by the fitting
algorithm.gModel.