SCALBN(3) BSD Programmer's Manual SCALBN(3)

## NAME

**scalbn**, **scalbnf** - exponent using FLT_RADIX

## LIBRARY

libm

## SYNOPSIS

**#include <math.h>**
*double*
**scalbn**(*double x*, *int n*);
*float*
**scalbnf**(*float x*, *int n*);

## DESCRIPTION

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 **#include <float.h>**
The rationale is efficiency; *r^n* is not computed explicitly.

## RETURN VALUES

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.

## SEE ALSO

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

## STANDARDS

The described functions conform to ISO/IEC 9899:1999 ("ISO C99").
MirOS BSD #10-current February 9, 2014 1

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