Evaluating signs of determinants using single-precision arithmetic

We propose a method to evaluate signs of $2\times 2$ and $3\times 3$ determinants with $b$-bit integer entries using only $b$ and $(b+1)$-bit arithmetic respectively. This algorithm has numerous applications in geometric computation and provides a general and practical approach to robustness. The algorithm has been implemented and experimental results show that it slows down the computing time by only a small factor only with respect to floating-point calculation.