Errata

1. Page 338, equation 16: The cross product AxC should be CxA. To see this, note that the vectors CxA and BxA become nearly parallel when the edge CB shrinks to zero, which makes the dot product approach one, and the angle alpha therefore approachs zero (as it should). As the formula appears in the paper, however (with AxC), the vectors become nearly opposite as the edge CB shrinks, which makes the angle alpha approach pi!