ilogb(3) - NetBSD Manual Pages

ILOGB(3)                NetBSD 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.  For-
     mally 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 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