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The traditional split-up into a low level language and a high level language in the design of computer algebra systems may become obsolete with the advent of more versatile computer languages. We describe GiNaC, a special-purpose system that deliberately denies the need for such a distinction. It is entirely written in C ++ and the user can interact with it… (More)
We present an overview of the research activities of the theoretical particle physics group at the University of Mainz on the calculation of massive one-and two-loop Feynman diagrams. The main objective of this research was to develop an automatic one-and two-loop calculation program package. A first version of such a program was recently realized by… (More)
GiNaC is a free framework that embeds symbolic manipulation consistently into the C++ programming language. It deliberately neglects the split-up into a low level language and a high level language, traditional in the design of computer algebra systems. The user usually interacts with GiNaC directly in C++. GiNaC was designed to provide efficient handling… (More)
We calculate the two-loop vertex function for the crossed topology, and for arbitrary masses and external momenta. We derive a double integral representation , suitable for a numerical evaluation by a Gaussian quadrature. Real and imaginary parts of the diagram can be calculated separately.