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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 nonzero real
floatingpoint number x as a signed integer value. Formally the return value is the inte
gral part of
log_r  x ,
where r is the radix of the machine's floatingpoint arithmetic defined by the FLT_RADIX
constant in <float.h>.
RETURN VALUES
As described above, upon successful completion, the functions return the exponent. Func
tionally this is the same as calling the corresponding 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 



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