- compute exponent using FLT_RADIX
c99 [ flag... ] file... -lm [ library... ] #include <math.h> double scalbln(double x, long n);
float scalblnf(float x, long n);
long double scalblnl(long double x, long n);
double scalbn(double x, int n);
float scalbnf(float x, int n);
long double scalbnl(long double x, int n);
These functions compute x * FLT_RADIXn efficiently, not normally by computing FLT_RADIXn explicitly.
Upon successful completion, these functions return x * FLT_RADIXn>.
If the result would cause overflow, a range error occurs and these functions return ±HUGE_VAL, ±HUGE_VALF, and ±HUGE_VALL (according to the sign of x) as appropriate for the return type of the function.
If x is NaN, a NaN is returned.
If x is ±0 or ±Inf, x is returned.
If x is 0, x is returned.
These functions will fail if:
The result overflows.
If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the overflow floating-point exception is raised.
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.
See attributes(5) for descriptions of the following attributes: