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| .\" $FreeBSD: src/lib/msun/man/ilogb.3,v 1.3 2005/11/17 13:00:00 ru Exp $ |
| .\" |
| .Dd November 6, 2005 |
| .Dt ILOGB 3 |
| .Os |
| .Sh NAME |
| .Nm ilogb , |
| .Nm ilogbf , |
| .Nm ilogbl , |
| .Nm logb , |
| .Nm logbf |
| .Nd extract exponent |
| .Sh LIBRARY |
| .Lb libm |
| .Sh SYNOPSIS |
| .In math.h |
| .Ft int |
| .Fn ilogb "double x" |
| .Ft int |
| .Fn ilogbf "float x" |
| .Ft int |
| .Fn ilogbl "long double x" |
| .Ft double |
| .Fn logb "double x" |
| .Ft float |
| .Fn logbf "float x" |
| .Sh DESCRIPTION |
| .Fn ilogb , |
| .Fn ilogbf |
| and |
| .Fn ilogbl |
| return |
| .Fa x Ns 's exponent |
| in integer format. |
| .Fn ilogb \*(Pm\*(If |
| returns |
| .Dv INT_MAX , |
| .Fn ilogb \*(Pm\*(Na |
| returns |
| .Dv FP_ILOGBNAN , |
| and |
| .Fn ilogb 0 |
| returns |
| .Dv FP_ILOGB0 . |
| .Pp |
| .Fn logb x |
| and |
| .Fn logbf x |
| return |
| .Fa x Ns 's exponent |
| in floating\-point format with the same precision as |
| .Fa x . |
| .Fn logb \*(Pm\*(If |
| returns +\*(If, and |
| .Fn logb 0 |
| returns -\*(If with a division by zero exception. |
| .Sh SEE ALSO |
| .Xr frexp 3 , |
| .Xr ieee 3 , |
| .Xr math 3 , |
| .Xr scalbn 3 |
| .Sh STANDARDS |
| The |
| .Fn ilogb , |
| .Fn ilogbf , |
| .Fn ilogbl , |
| .Fn logb |
| and |
| .Fn logbf |
| routines conform to |
| .St -isoC-99 . |
| .Fn logb |
| and |
| .Fn logbf |
| implement the logb function recommended by |
| .St -ieee754 . |
| .Sh HISTORY |
| The |
| .Fn logb |
| function appeared in |
| .Bx 4.3 . |
| The |
| .Fn ilogb |
| function appeared in |
| .Fx 1.1.5 . |
| The |
| .Fn ilogbf |
| and |
| .Fn logbf |
| functions appeared in |
| .Fx 2.0 . |
| The |
| .Fn ilogbl |
| function appeared in |
| .Fx 5.4 . |