Index for Section 3

Alphabetical listing for F

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frexp(3)
NAME
  frexp, ldexp, logb, scalb - Manipulate floating-point numbers

SYNOPSIS
  #include <math.h>

  double frexp(
	  double x,
	  int *n );

  float frexpf(
	  float x,
	  int *n );

  long double frexpl(
	  long double x,
	  int *n );

  double ldexp(
	  double y,
	  int n );

  float ldexpf(
	  float y,
	  int n );

  long double ldexpl(
	  long double y,
	  int n );

  double logb(
	  double x );

  float logbf(
	  float x );

  long double logbl(
	  long double x );

  double scalb(
	  double x,
	  double n );

  float scalbf(
	  float x,
	  float n );

  long double scalbl(
	  long double x,
	  long double n );

LIBRARY
  Math Library (libm)

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  frexp():  XPG4

  ldexp():  XPG4

  logb():  XPG4-UNIX

  scalb():  XPG4-UNIX

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

DESCRIPTION
  Every nonzero number can be written uniquely as the normalized mantissa
  (fraction) z times 2 raised to the power p, where the absolute value of z
  is in the range [0.5, 1.0), and the exponent p, is an integer.

  The frexp(), frexpf(), and frexpl() functions break a floating-point number
  into a normalized fraction and an integral power of 2. The functions store
  the integer in the int object pointed to by the n parameter and return the
  fraction part.

  The ldexp(), ldexpf(), and ldexpl() functions multiply a floating-point
  number, y, by an integral power of 2.

  The logb(), logbf(), and logbl() functions return a signed integer
  converted to double-precision floating-point and so chosen that 1 <=
  |x|/2**n < 2 unless x = 0 or |x| = infinity or x lies between 0 and the
  Underflow Threshold.

  IEEE 754 defines logb(+infinity) = +infinity and logb(0) = -infinity. The
  latter is required to signal Division-by-Zero.

  The scalb(), scalbf(), and scalbl() functions are defined as x*(2**n) for
  integer n.

  The following table describes function behavior in response to exceptional
  arguments:

  _________________________________________________________________________
  Function			  Exceptional Argument	   Routine Behavior
  _________________________________________________________________________
				  |x| = infinity	   Invalid argument

  frexp(), frexpf(), frexpl()
				  |x| = infinity	   Invalid argument

  logb(), logbf(), logbl()
							   Overflow

  scalb(), scalbf(), scalbl()

				  x*(2**n) > max_float
							   Underflow

  scalb(), scalbf(), scalbl()

				  x*(2**n) < min_float
							   Overflow

  ldexp(), ldexpf(), ldexpl()

				  x*(2**n) > max_float
							   Underflow

  ldexp(), ldexpf(), ldexpl()

				  x*(2**n) < min_float
  _________________________________________________________________________

  The following table lists boundary values used by these functions:

  ___________________________________________________________________
  Value Name   Data Type   Hexadecimal Value   Decimal Value
  ___________________________________________________________________
  max_float    S_FLOAT	   7F7FFFFF	       3.402823e38
	       T_FLOAT	   7FEFFFFFFFFFFFFF    1.797693134862316e308
  min_float    S_FLOAT	   00000001	       1.4012985e-45
	       T_FLOAT	   0000000000000001    4.940656458412465e-324
  ___________________________________________________________________

Index for Section 3

Alphabetical listing for F

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