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, then errno shall be set to ERANGE. 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, then errno shall be set to ERANGE. 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

See Also

  1. Standard library functions
  2. Table of Contents