SCALBN(3) BSD Programmer's Manual SCALBN(3)
scalbn, scalbnf, scalbnl - exponent using FLT_RADIX
libm
#include <math.h>
double
scalbn(double x, int n);
float
scalbnf(float x, int n);
long double
scalbnl(long double x, int n);
The scalbn(), scalbnf(), and scalbnl() functions compute x * r^n, where r
is the radix of the machine's floating point arithmetic, defined by the
FLT_RADIX constant in #include <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 ac-
cording 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").
MirOS BSD #10-current September 18, 2011 1
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