Compared to previous version GBT 7.0 is a complete rewrite - based on experience accumulated since 1993, when GBT 1.0 was launched.
The main differences compared with GBT 6.1 are:

• Different polytope representation matrix is used. This was necessary for the new way of computational error control. There are format conversion routines gbt627 and gbt726 to ensure compatibility with GBT 6.1
• It is possible to handle polytopes of arbitrary topological structure. Polytopes with vertices at which more than "the dimension" number of facets meet, can now be worked with. Also polytopes with lower dimension than that of the representation space, can be used and computed with. This allows for arbitrary affine transformations of polytopes to be computed.
• For numerical reasons, which may appear first a limitation to practice in GBT 6.1, only bounded polyhedra are considered. This is a necessity which is a consequence of the digital arithmetic used, and the problem would persist whether floating point (in case of MATLAB) or fixed-point arithmetic (in case of some DSPs) would be used. Numerical errors are monitored in all routines to allow nearly bug-free operation. At the heart of the package is a convex hull algorithm, similar to the quickhull algorithm but with special care taken for numerical reliability and efficiency of computation.

Associated with the package are User's and Reference Manual there are two further manuals: the Applications Manual for the users of the package in various fields and the Programming Manual which gives detailed comments on every part of the code and is is intended for the advanced user who needs modifications or wants to compile the package in C for use on DSPs. Queries on GBT 7.0 can be addressed to gbt [AT) sysbrain.com .