Index for Section 3

Alphabetical listing for F

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

LIBRARY
  Math Library (libm.a)

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);

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
  _____________________________________________________________________
  frexp(), frexpf(), frexpl()	|x| = infinity	       Invalid argument
  logb(), logbf(), logbl()	|x| = infinity	       Invalid argument
  scalb(), scalbf(), scalbl()	x*(2**n) > max_float   Overflow
  scalb(), scalbf(), scalbl()	x*(2**n) < min_float   Underflow
  ldexp(), ldexpf(), ldexpl()	x*(2**n) > max_float   Overflow
  ldexp(), ldexpf(), ldexpl()	x*(2**n) < min_float   Underflow
  _____________________________________________________________________

  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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