logbf(3) [osx man page]

LOGB(3) 						   BSD Library Functions Manual 						   LOGB(3)

NAME

     logb -- return exponent as a floating-point number

SYNOPSIS

     #include <math.h>

     double
     logb(double x);

     long double
     logbl(long double x);

     float
     logbf(float x);

DESCRIPTION

     The logb() functions return the exponent of x, represented as a floating-point number.

SPECIAL VALUES

     logb(+-0) returns -infinity and raises the "divide-by-zero" floating-point exception.

     logb(+-infinity) returns +infinity.

VECTOR OPERATIONS

     If you need to apply the logb() functions to SIMD vectors or arrays, using the following functions provided by the Accelerate.framework may
     give significantly better performance:

     #include <Accelerate/Accelerate.h>

     vFloat vlogbf(vFloat x);
     void vvlogbf(float *y, const float *x, const int *n);
     void vvlogb(double *y, const double *x, const int *n);

SEE ALSO

     ilogb(3) log(3) math(3)

STANDARDS

     The logb() functions conform to ISO/IEC 9899:2011.

BSD
								  August 21, 2012							       BSD

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