expm1(3) Library Functions Manual expm1(3) expm1, expm1f, expm1l - 1 (libm -lm) #include double expm1(double x); float expm1f(float x); long double expm1l(long double x); glibc ( feature_test_macros(7)): expm1(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 500 || /* glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE expm1f(), expm1l(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE exp(x) - 1 x -- exp(x) - 1 . exp(x) - 1. x (NaN) NaN. x +0 (-0) +0 (-0). x . x -1. -HUGE_VAL -HUGE_VALF -HUGE_VALL . math_error(7) . : errno ERANGE ( BUGS). (FE_OVERFLOW). attributes(7). +------------+------------------------------------+--------------------+ || | | +------------+------------------------------------+--------------------+ |expm1(), | | MT-Safe | |expm1f(), | | | |expm1l() | | | +------------+------------------------------------+--------------------+ C11, POSIX.1-2008. C99 POSIX.1-2001. BSD. glibc 2.17 ( x86 x86_64) expm1() x ( -1). glibc 2.11 expm1() NaN x . glibc 2.11 glibc errno ERANGE . exp(3), log(3), log1p(3) 3 . . : . 6.18 8 2026 expm1(3)