A method of manipulating a block diagram model with a plurality of graphical modeling components by defining an open loop anywhere on the block diagram model is provided. Graphical modeling components in series with the open loop may be automatically recognized and a plurality of parameters of the graphical modeling components in series with the open loop may be displayed on a display device. A user may simultaneously tune the parameters of the graphical modeling components in series with the open loop. Factorization points breaking the block diagram model in two disconnected parts may be identified in the block diagram model. A virtual graphical model may be generated by replacing a pattern of the graphical modeling components between two factorization points with a single graphical modeling component representing the pattern.