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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(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Interface Stability | Standard |
| MT-Level | MT-Safe |
frexp(3M), isnan(3M), modf(3M), attributes(5), standards(5)