scalbln(3) — Linux manual page


SCALBLN(3)              Linux Programmer's Manual             SCALBLN(3)

NAME         top

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

SYNOPSIS         top

       #include <math.h>

       double scalbln(double x, long exp);
       float scalblnf(float x, long exp);
       long double scalblnl(long double x, long exp);

       double scalbn(double x, int exp);
       float scalbnf(float x, int exp);
       long double scalbnl(long double x, int exp);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see

       scalbln(), scalblnf(), scalblnl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE

       scalbn(), scalbnf(), scalbnl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION         top

       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

RETURN VALUE         top

       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         top

       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

       Range error, underflow
              errno is set to ERANGE.  An underflow floating-point
              exception (FE_UNDERFLOW) is raised.

VERSIONS         top

       These functions first appeared in glibc in version 2.1.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface                             Attribute     Value   │
       │scalbn(), scalbnf(), scalbnl(),       │ Thread safety │ MT-Safe │
       │scalbln(), scalblnf(), scalblnl()     │               │         │

CONFORMING TO         top

       C99, POSIX.1-2001, POSIX.1-2008.

NOTES         top

       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

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

BUGS         top

       Before glibc 2.20, these functions did not set errno for range

SEE ALSO         top

       ldexp(3), scalb(3)

COLOPHON         top

       This page is part of release 5.13 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at

                               2021-03-22                     SCALBLN(3)

Pages that refer to this page: ldexp(3)scalb(3)