- load exponent of a radix-independent floating-point number
c99 [ flag... ] file... -lm [ library... ] #include <math.h> double scalb(double x, double n);
float scalbf(float x, float n);
long double scalbl(long double x, long double n);
These functions compute x * rn, where r is the radix of the machine's floating point arithmetic. When r is 2, scalb() is equivalent to ldexp(3M). The value of r is FLT_RADIX which is defined in <float.h>.
Upon successful completion, the scalb() function returns x * rn.
If x or n is NaN, a NaN is returned.
If n is 0, x is returned.
If x is ±Inf and n is not -Inf, x is returned.
If x is ±0 and n is not +Inf, x is returned.
If x is ±0 and n is +Inf, a domain error occurs and a NaN is returned.
If x is ±Inf and n is -Inf, a domain error occurs and a NaN is returned.
If the result would cause an overflow, a range error occurs and ±HUGE_VAL (according to the sign of x) is returned.
These functions will fail if:
If x is 0 and n is +Inf, or x is Inf and n is -Inf.
If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception is raised.
The result would overflow.
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:
The scalb() function is Standard. The scalbf() and scalbl() functions are Stable.