ILOGB(3)               FreeBSD 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 +infinity,
     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 implement 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

FreeBSD 13.1-RELEASE-p6        December 16, 2007       FreeBSD 13.1-RELEASE-p6