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exp, expf, expl - exponential function


c99 [ flag… ] file-lm [ library… ]
#include <math.h>

double exp(double x);

float expf(float x);

long double expl(long double x);


These functions compute the base-e exponential of x.


Upon successful completion, these functions return the exponential value of x.

If the correct value would cause overflow, a range error occurs and exp(), expf(), and expl() return HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively.

If x is NaN, a NaN is returned.

If x is ±0, 1 is returned.

If x is +Inf, x is returned.

For exceptional cases, matherr(3M) tabulates the values to be returned by exp() as specified by SVID3 and XPG3. See standards(7).


These functions will fail if:

Range Error

The result overflows.

If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the overflow floating-point exception is raised.

The exp() function sets errno to ERANGE if the result overflows.


An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.

An application can also set errno to 0 before calling exp(). On return, if errno is non-zero, an error has occurred. The expf() and expl() functions do not set errno.


See attributes(7) for descriptions of the following attributes:


math.h(3HEAD), mp(3MP), feclearexcept(3M), fetestexcept(3M), isnan(3M), log(3M), matherr(3M), attributes(7), standards(7)

solaris/exp.3m.txt · Last modified: 2023/07/19 08:58 by A User Not Logged in