Vincent Lefèvre Damien Stehlé Paul Zimmermann Worst Cases for the Exponential Function in the IEEE 754r decimal64 Format. 114-126 2008 Reliable Implementation of Real Number Algorithms http://dx.doi.org/10.1007/978-3-540-85521-7_7 conf/dagstuhl/2008real db/conf/dagstuhl/real2008.html#LefevreSZ08