sunos man page for ilogb

ilogb(3M)						  Mathematical Library Functions						 ilogb(3M)

NAME
       ilogb, ilogbf, ilogbl - return an unbiased exponent

SYNOPSIS
       cc [ flag... ] file... -lm [ library... ]
       #include <math.h>

       int ilogb(double x);

       int ilogbf(float x);

       int ilogbl(long double x);

DESCRIPTION
       These  functions  return  the exponent part of their argument x.  Formally, the return value is the integral part of  logr| x | as a signed
       integral value, for non-zero x, where r is the radix of the machine's floating point arithmetic, , which is the value of FLT_RADIX  defined
       in <float.h>.

RETURN VALUES
       Upon  successful  completion,  these  functions return the exponent part of x as a signed integer value. They are equivalent to calling the
       corresponding logb(3M) function and casting the returned value to type int.

       If x is 0, the value FP_ILOGB0 is returned. For SUSv3-conforming applications (see standards(5)), a domain error occurs.

       If x is +-Inf, the value INT_MAX is returned. For SUSv3-conforming applications, a domain error occurs.

       If x is NaN, the value FP_ILOGBNAN is returned. For SUSv3-conforming applications, a domain error occurs.

ERRORS
       These functions will fail if:

       Domain Error    The x argument is zero, NaN, or +-Inf.

		       If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the  invalid  floating-point  exception	is
		       raised.

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO
       feclearexcept(3M), fetestexcept(3M), limits.h(3HEAD), logb(3M), math.h(3HEAD), scalb(3M), attributes(5), standards(5)

SunOS 5.10							    1 Nov 2003								 ilogb(3M)