SCALBN(3) Library Functions Manual SCALBN(3)

scalbn, scalbnf, scalbnl — exponent using FLT_RADIX

Math Library (libm, -lm)

#include <math.h>

double
scalbn(double x, int n);

float
scalbnf(float x, int n);

long double
scalbnl(long double x, int n);

The (), (), and () functions compute x * r^n, where r is the radix of the machine's floating point arithmetic, defined by the FLT_RADIX constant in <float.h>. The rationale is efficiency; r^n is not computed explicitly.

As described above, upon successful completion, the described functions return the exponent computed using FLT_RADIX. Otherwise the following may occur:

  1. When the result would cause an overflow, a range error occurs and ±HUGE_VAL, ±HUGE_VALF, or ±HUGE_VALL is returned according to the sign of x and the return type of the corresponding function.
  2. When the correct value would cause an underflow and it is not representable, a range error occurs and either 0.0 or an implementation-defined value is returned. When an underflow occurs but the correct value is representable, a range error occurs but the correct value is returned.
  3. If x is ±0 or ±Inf, x is returned. Likewise, if n is zero, x is returned. If x is NaN, NaN is returned.

exp(3), frexp(3), ldexp(3), math(3)

The described functions conform to ISO/IEC 9899:1999 (“ISO C99”).

September 18, 2011 NetBSD 11.0