Callbacks

During the search the user's model may interact with the solver at certain predefined points by means of callback functions. This functionality is particularly useful to retrieve solution information for intermediate solutions during an optimization run as shown in the model freqasgn.mos (Section abs and distance: Frequency assignment). Other than this solution callback, the user may set functions that will be called at every branch or at every node (see the Xpress Kalis reference manual for further detail).