Quick summary of the talk: A specialist number representation is made for exact representation of values in geometric calculations (think CAD). Numbers are rep

Quick summary of the talk: A specialist number representation is made for exact representation of values in geometric calculations (think CAD). Numbers are represented as sums of rational multiples of cos(iπ/2n). Exact summation, multiplication and division (not shown) of these quantities are possible, and certain edge-cases (eg. sqrt) have special-case handling. The system was integrated into and tested on an existing codebase. The speaker was also one of the authors of Herbie, if other people remember that.