exp(3) Library Functions Manual exp(3) NAME exp, expf, expl - base-e exponential function LIBRARY Math library (libm, -lm) SYNOPSIS #include double exp(double x); float expf(float x); long double expl(long double x); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): expf(), expl(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE DESCRIPTION These functions return the value of e (the base of natural logarithms) raised to the power of x. RETURN VALUE On success, these functions return the exponential value of x. If x is a NaN, a NaN is returned. If x is positive infinity, positive infinity is returned. If x is negative infinity, +0 is returned. If the result underflows, a range error occurs, and zero is returned. If the result overflows, a range error occurs, and the functions return +HUGE_VAL, +HUGE_VALF, or +HUGE_VALL, respectively. ERRORS See math_error(7) for information on how to determine whether an error has occurred when calling these functions. The following errors can occur: Range error, overflow errno is set to ERANGE. An overflow floating-point exception (FE_OVERFLOW) is raised. Range error, underflow errno is set to ERANGE. An underflow floating-point exception (FE_UNDERFLOW) is raised. ATTRIBUTES For an explanation of the terms used in this section, see attributes(7). +--------------------------------------------+---------------+---------+ |Interface | Attribute | Value | +--------------------------------------------+---------------+---------+ |exp (), expf (), expl () | Thread safety | MT-Safe | +--------------------------------------------+---------------+---------+ STANDARDS C11, POSIX.1-2008. HISTORY C99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD, C89. SEE ALSO cbrt(3), cexp(3), exp10(3), exp2(3), expm1(3), sqrt(3) Linux man-pages 6.9.1 2024-05-02 exp(3)