LDEXP(3M) Mathematical Library Functions LDEXP(3M)

ldexp, ldexpf, ldexpl - load exponent of a floating point number

c99 [ flag... ] file... -lm [ library... ]
#include <math.h>
double ldexp(double x, int exp);

float ldexpf(float x, int exp);

long double ldexpl(long double x, int exp);

These functions computes the quantity x* 2^exp.

Upon successful completion, these functions return x multiplied by 2 raised to the power exp.

If these functions would cause overflow, a range error occurs and ldexp(), ldexpf(), and ldexpl() return ±HUGE_VAL, ±HUGE_VALF, and ±HUGE_VALL (according to the sign of x), respectively.

If x is NaN, a NaN is returned.

If x is ±0 or ±Inf, x is returned.

If exp is 0, x is returned.

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 ldexp() 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 ldexp(). On return, if errno is non-zero, an error has occurred. The ldexpf() and ldexpl() functions do not set errno.

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

Interface Stability Standard
MT-Level MT-Safe

frexp(3M), isnan(3M), modf(3M), attributes(7), standards(7)

July 12, 2006 SunOS 5.11