IEEE 754-2008, on page 52, says that acos(1) is +0 What is the preferred exponent of that +0? --- Fred J. Tydeman Tydeman Consulting tydeman@xxxxxxxxx Testing, numerics, programming +1 (775) 358-9748 Vice-chair of PL22.11 (ANSI "C") Sample C99+FPCE tests: http://www.tybor.com Savers sleep well, investors eat well, spenders work forever.