SCALBN(3) BSD Programmer's Manual SCALBN(3)
scalbn, scalbnf - exponent using FLT_RADIX
#include <math.h> double scalbn(double x, int n); float scalbnf(float x, int n);
The scalbn() and scalbnf() functions compute x * r^n, where r is the ra- dix 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 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 February 9, 2014 1
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