Linux manual pages Section 3: Subroutines  

Name

scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl — multiply floating-point number by integral power of radix

Synopsis

#include <math.h>
double scalbln( double x,
  long int exp);
 
float scalblnf( float x,
  long int exp);
 
long double scalblnl( long double x,
  long int exp);
 
double scalbn( double x,
  int exp);
 
float scalbnf( float x,
  int exp);
 
long double scalbnl( long double x,
  int exp);
 
[Note] Note
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
scalbln(), scalblnf(), scalblnl():
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
scalbn(), scalbnf(), scalbnl():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
[Note] Note

Link with −lm.

DESCRIPTION

These functions multiply their first argument x by FLT_RADIX (probably 2) to the power of exp, that is:

    x * FLT_RADIX ** exp

The definition of FLT_RADIX can be obtained by including <float.h>

RETURN VALUE

On success, these functions return x * FLT_RADIX ** exp.

If x is a NaN, a NaN is returned.

If x is positive infinity (negative infinity), positive infinity (negative infinity) is returned.

If x is +0 (−0), +0 (−0) is returned.

If the result overflows, a range error occurs, and the functions return HUGE_VAL, HUGE_VALF, or HUGE_VALL, respectively, with a sign the same as x.

If the result underflows, a range error occurs, and the functions return zero, with a sign the same as x.

ERRORS

See math_error(7) for information on how to determine whether an error has occurred when calling these functions.

The following errors can occur:

Range error, overflow

An overflow floating-point exception (FE_OVERFLOW) is raised.

Range error, underflow

An underflow floating-point exception (FE_UNDERFLOW) is raised.

These functions do not set errno.

VERSIONS

These functions first appeared in glibc in version 2.1.

ATTRIBUTES

Multithreading (see pthreads(7))

The scalbn(), scalbnf(), scalbnl(), scalbln(), scalblnf(), and scalblnl() functions are thread-safe.

CONFORMING TO

C99, POSIX.1-2001.

NOTES

These functions differ from the obsolete functions described in scalb(3) in the type of their second argument. The functions described on this page have a second argument of an integral type, while those in scalb(3) have a second argument of type double.

If FLT_RADIX equals 2 (which is usual), then scalbn() is equivalent to ldexp(3).

SEE ALSO

ldexp(3), scalb(3)

COLOPHON

This page is part of release 3.52 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man−pages/.


  Copyright 2004 Andries Brouwer <aebcwi.nl>.
and Copyright 2008, Linux Foundation, written by Michael Kerrisk
    <mtk.manpagesgmail.com>

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