ilogb(3) [netbsd man page]

ILOGB(3)						   BSD Library Functions Manual 						  ILOGB(3)

NAME

     ilogb, ilogbf, ilogbl -- an unbiased exponent

LIBRARY

     Math Library (libm, -lm)

SYNOPSIS

     #include <math.h>

     int
     ilogb(double x);

     int
     ilogbf(float x);

     int
     ilogbl(long double x);

DESCRIPTION

     The ilogb(), ilogbf(), and ilogbl() functions return the exponent of the non-zero real floating-point number x as a signed integer value.
     Formally the return value is the integral part of

	   log_r | x |,

     where r is the radix of the machine's floating-point arithmetic defined by the FLT_RADIX constant in <float.h>.

RETURN VALUES

     As described above, upon successful completion, the functions return the exponent.  Functionally this is the same as calling the correspond-
     ing logb(3) function and casting the return value to int.

     The following special cases may occur:

	   1.	If x is zero, the value of FP_ILOGB0 is returned and a domain error occurs.

	   2.	If x is infinite, a domain error occurs and the value of INT_MAX is returned.

	   3.	If x is NaN, a domain error is raised and the value of FP_ILOGBNAN is returned.

	   4.	If the correct value is outside the range of the return type, a domain error occurs but an unspecified value is returned.

SEE ALSO

     ilog2(3), logb(3), math(3)

STANDARDS

     The described functions conform to ISO/IEC 9899:1999 (``ISO C99'').

BUGS

     Neither FP_ILOGB0 nor FP_ILOGBNAN is defined currently in NetBSD.

BSD
								   July 29, 2011							       BSD

Check Out this Related Man Page

ILOGB(3)						   BSD Library Functions Manual 						  ILOGB(3)

NAME

     ilogb, ilogbf, ilogbl, logb, logbf, logbl -- extract exponent

LIBRARY

     Math Library (libm, -lm)

SYNOPSIS

     #include <math.h>

     int
     ilogb(double x);

     int
     ilogbf(float x);

     int
     ilogbl(long double x);

     double
     logb(double x);

     float
     logbf(float x);

     long double
     logbl(long double x);

DESCRIPTION

     ilogb(), ilogbf() and ilogbl() return x's exponent in integer format.  ilogb(+-infinity) returns INT_MAX, ilogb(+-NaN) returns FP_ILOGBNAN,
     and ilogb(0) returns FP_ILOGB0.

     logb(x), logbf(x), and logbl(x) return x's exponent in floating-point format with the same precision as x.  logb(+-infinity) returns +infin-
     ity, and logb(0) returns -infinity with a division by zero exception.

SEE ALSO

     frexp(3), ieee(3), math(3), scalbn(3)

STANDARDS

     The ilogb(), ilogbf(), ilogbl(), logb(), logbf(), and logbl() routines conform to ISO/IEC 9899:1999 (``ISO C99'').  The latter three imple-
     ment the logb function recommended by IEEE Std 754-1985.

HISTORY

     Function	First Appeared In
     logb()	4.3BSD
     ilogb()	FreeBSD 1.1.5
     ilogbf()	FreeBSD 2.0
     logbf()	FreeBSD 2.0
     ilogbl()	FreeBSD 5.4
     logbl()	FreeBSD 8.0

BSD
								 December 16, 2007							       BSD

Linux and UNIX Man Pages

ilogb(3) [netbsd man page]

Check Out this Related Man Page