Synopsis
#include <math.h>
double exp(double x);
float expf(float x);
long double expl(long double x);
Status
Partially implemented
Conformance
IEEE Std 1003.1-2017
Description
These functions shall compute the base e exponential of x.
An application wishing to check for error situations should set errno to zero and call
feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or
fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.
Return value
Upon successful completion, these functions shall return the exponential value of x.
If the correct value would cause overflow, a range error shall occur and exp(), expf(), and expl() shall
return the value of the macro HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively.
If the correct value would cause underflow, and is not representable, a range error may occur, and exp(), expf(), and expl() shall return 0.0, or (if the IEC 60559 Floating-Point option is not supported) an
implementation-defined value no greater in magnitude than DBL_MIN, FLT_MIN, and LDBL_MIN, respectively.
If
x is NaN, a NaN shall be returned.
If x is ±0, 1 shall be returned.
If x is -Inf, +0 shall be returned.
If x is +Inf, x shall be returned.
If the correct value would cause underflow, and is representable, a range error may occur and the correct value shall be returned.
Errors
These functions shall fail if:
- Range Error - The result overflows.
If the integer expression
(math_errhandling & MATH_ERRNO)is non-zero, thenerrnoshall be set toERANGE. If the integer expression(math_errhandling & MATH_ERREXCEPT)is non-zero, then the overflow floating-point exception shall be raised.
These functions may fail if:
- Range Error - The result underflows.
If the integer expression
(math_errhandling & MATH_ERRNO)is non-zero, thenerrnoshall be set toERANGE. If the integer expression(math_errhandling & MATH_ERREXCEPT)is non-zero, then the underflow floating-point exception shall be raised.
Tests
Untested
Known bugs
None