OS_NS_math.h File Reference

#include "ace/os_include/os_math.h"

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Namespaces
namespace	ACE_OS
	This namespace defines an OS independent programming API that shields developers from nonportable aspects of writing efficient system programs on Win32, POSIX and other versions of UNIX, and various real-time operating systems.
Functions
double	ace_log2_helper (double x)
ACE_NAMESPACE_INLINE_FUNCTION double	ACE_OS::floor (double x)
	This method computes the largest integral value not greater than x.
ACE_NAMESPACE_INLINE_FUNCTION double	ACE_OS::ceil (double x)
	This method computes the smallest integral value not less than x.
ACE_NAMESPACE_INLINE_FUNCTION double	ACE_OS::log2 (double x)
	This method computes the base-2 logarithm of x.

---

Detailed Description

Id

OS_NS_math.h 78447 2007-05-23 04:35:10Z ossama

Author:

Douglas C. Schmidt <schmidt@cs.wustl.edu>

Jesper S. M|ller<stophph@diku.dk>

and a cast of thousands...

Originally in OS.h.

Definition in file OS_NS_math.h.

---

Function Documentation

double ace_log2_helper

(

double

x

)

[inline]

Definition at line 45 of file OS_NS_math.h.

{
#if defined (log2)
  return log2 (x);
#undef log2
#else
#  if !defined (ACE_LACKS_LOG2)
  return ACE_STD_NAMESPACE::log2 (x);
#  else
  /*
    ==================================================================

                log (x)
                   k
      log (x) = -------
         b      log (b)
                   k

    meaning the binary logarithm of x using the natural logarithm, for
    example, is:


                log (x)
                   e
      log (x) = -------
         2      log (2)
                   e

    ==================================================================
   */

  // Precomputed value of 1/log(2.0).  Saves an expensive division and
  // computing log(2.0) in each call.
  double const _1_ln2 = 1.442695040888963407359924681002;

  return log (x) * _1_ln2;
#  endif /* !ACE_LACKS_LOG2 */
#endif /* defined (log2) */
}