The problem of detecting gravitational radiation is receiving considerable attention with the construction of new detectors in the United States, Europe, and Japan. The theoretical modeling of the wave forms that would be produced in particular systems will expedite the search for and analysis of detected signals. The characteristic formulation of GR is implemented to obtain an algorithm capable of evolving black holes in 3D asymptotically flat spacetimes. Using compactification techniques, future null infinity is included in the evolved region, which enables the unambiguous calculation of the radiation produced by some compact source. A module to calculate the waveforms is constructed and included in the evolution algorithm. This code is shown to be second-order convergent and to handle highly non-linear spacetimes. In particular, we have shown that the code can handle spacetimes whose radiation is equivalent to a galaxy converting its whole mass into gravitational radiation in one second. We further use the characteristic formulation to treat the region close to the singularity in black hole spacetimes. The code carefully excises a region surrounding the singularity and accurately evolves generic black hole spacetimes with apparently unlimited stability.
In the above UML class diagram , the Client class that requires ProductA and ProductB objects doesn't instantiate the ProductA1 and ProductB1 classes directly. Instead, the Client refers to the AbstractFactory interface for creating objects, which makes the Client independent of how the objects are created (which concrete classes are instantiated). The Factory1 class implements the AbstractFactory interface by instantiating the ProductA1 and ProductB1 classes.
The UML sequence diagram shows the run-time interactions: The Client object calls createProductA() on the Factory1 object, which creates and returns a ProductA1 object. Thereafter, the Client calls createProductB() on Factory1 , which creates and returns a ProductB1 object.