On GEANT-DIRAC multiple scattering in thin layers of DIRAC setup

In DIRAC setup there are a lot of thin materials such as cathodes, anodes, wires, strips and so on. The GEANT3 program for Monte-Carlo simulation deals with REAL*4 numbers only and therefore for thin layers the rounding errors can be significant. The aim of this work is to study of rounding error influence and to change, if need, the GEANT-DIRAC code to achieve a correct description of multiple scattering for thin layers in this program.