Manpages - scalbln.3

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

  #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 *feature_test_macros*(7)):

*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

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>.

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.

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

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

These functions first appeared in glibc in version 2.1.

For an explanation of the terms used in this section, see *attributes*(7).

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

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).

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

*ldexp*(3), *scalb*(3)

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