/* * Written 2005 by Gregory W. Chicares . * Adapted to float by Danny Smith . * Public domain. * * F2XM1's input is constrained to (-1, +1), so the domain of * 'x * LOG2EL' is (-LOGE2L, +LOGE2L). Outside that domain, * delegating to exp() handles C99 7.12.6.3/2 range errors. * * Constants from moshier.net, file cephes/ldouble/constl.c, * are used instead of M_LN2 and M_LOG2E, which would not be * visible with 'gcc std=c99'. The use of these extended precision * constants also allows gcc to replace them with x87 opcodes. */ #include /* expl() */ #include "cephes_mconf.h" float expm1f (float x) { if (fabsf(x) < LOGE2L) { x *= LOG2EL; __asm__("f2xm1" : "=t" (x) : "0" (x)); return x; } else return expf(x) - 1.0F; }