Exact geometric computation in LEDA

Almost all geometric algorithms are based on the RealRAM model. Implementors often simply replace the exact real arithmetic of this model by fixed precision arithmetic, thereby making correct algorithms incorrect. Two approaches have been taken to remedy this sit uation. The first approach is redesigning geometric algorithms for fixed precision arithmetic. The redesign is difficult and can inherently not lead to exact results. Moreover it prevents application areas from making use of the rich literature of geometric algorithms developed in computational geometry. The other approach advocat es the use of exact real arithmetic.