freebsd man page for ilogb

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